Recent advances in electrochemical atomic force microscopy will be presented, with a focus on deciphering in situ an electrocatalyst’s morphological, structural, electrical and chemical properties at nanometer- and atomic-scale resolution. Selected results include unraveling the surface structure of state-of-the-art electrocatalysts during CO₂RR, COR, and OER, as well as probing ion-induced viscosity variations in nanoconfined electrolytes alongside with a material’s local electrical conductivity. Complementary spectroscopic approaches, including in situ ATR-SEIRAS and on-line DEMS, provide direct molecular-level insights into reaction intermediates and interfacial hydration layer structures during CO₂RR. A perspective will be given on multimodal approaches for nanoscale catalysis and rational innovation of energy conversion materials.

There has been a growing recognition that not only electrocatalysts but electrolytes influence the activity of surface electrocatalytic reactions. Therefore, understanding the electrolyte-electrode interface under realistic operating conditions is critical to designing active and stable electrochemical devices. The past few decades of research have focused on developing a range of spectroscopic and imagining tools to enable the study of the chemical and structural changes at the electrolyte-electrode interface. Here, we introduce operando surface-enhanced infrared absorption spectroscopy (SEIRAS), a promising lab-based tool for gaining a molecular-level understanding of interfacial electrochemical processes.

This talk will bring the most recent understanding of the electrochemical interface during the operation of energy storage (ex., lithium-ion battery) and electrolysis (ex., electrochemical CO2 reduction reaction) applications using operando SEIRAS. We will highlight how the holistic information about the nature of the electrolyte-electrode interface can provide additional knobs to tune the reactions, leading to further improvements in activity and stability for energy applications. Also, fundamentals and experimental tips for operando SEIRAS will be explained, which is essential for those interested in introducing operando SEIRAS to probe your electrochemical system.

Abstract: In the relentless pursuit of advancing electrochemical technologies, gaining a profound understanding of the intricate dynamics governing nano alloy catalysts during reduction reactions, such as the electrochemical CO2 reduction reaction (CO2RR) or oxygen reduction reaction (ORR), emerges as a pivotal endeavor. This presentation delves into a pioneering approach employing direct imaging techniques, specifically focused on copper-based/platinum-based alloys, utilizing in situ electrochemical transmission electron microscopy (TEM). The objective is to illuminate the evolving nanostructures of these catalysts in real-time under the dynamic conditions of electrochemical reduction reactions.

Through the application of this cutting-edge technique, we aim to unravel the intricate interplay between catalyst morphology and electrochemical performance. This comprehensive exploration provides crucial insights that extend beyond mere observation, offering a deeper understanding of the structural transformations occurring during dynamic electrochemical processes. The outcomes of this study are anticipated to offer valuable guidance for optimizing catalyst design strategies, ultimately leading to the enhancement of overall electrochemical performance and stability.

Electrocatalysis, whose reaction venue locates at the electrode-electrolyte interface, is controlled by electron transfer across the electric double layer, envisaging a mechanistic link between the electrocatalytic property and the EDL structure. One of the most intriguing questions is the mechanistic role of the alkali metal cation at the electrode-electrolyte interface, often referred to as the “cation effect”. In this presentation, we show that the identity of the alkali metal cation not only influences catalytic activity and selectivity, but can also directly affect electrode stability using an online inductively coupled plasma mass spectrometer coupled to an electrochemical flow cell. An increasing amount of Pt dissolution during cyclic voltammetry was found as the atomic number of alkali metal cations decreased. To explain this observation, various control experiments and computational studies were performed to explore potential scenarios such as changes in oxophilicity, electric field strength, and ion pairing. With a comprehensive understanding of alkali metal identity-dependent Pt dissolution, we propose a conceptual strategy for better electrocatalysis with prolonged catalytic durability.

Electrochemical solid-liquid interfaces (SLI) are extremely complex and dynamic. SLI plays a significant role in dictating both charge transfer dynamics and selectivity of reaction pathways at any given electrochemical interface. Probing the structure and arrangement of interfacial ion and solvent molecules in-situ with nanoscale resolution is crucial to understand the SLI and develop efficient electrocatalysts.

Electrochemical atomic force microscopy (EC-AFM) technique offers in-situ/operando correlative measurements that can probe SLI with nanometer spatial resolution, providing access to nanoscale heterogeneities. In this contribution, I will highlight the use of EC-AFM as an interfacial force sensor to map the interfacial adhesion forces in addition to the local topography of the electrode under study. As the electrode surface charge is tuned by external applied bias, the local SLI structure is modulated, which leads to quantifiable changes in the adhesion forces mapped by the EC-AFM. Adhesion forces extracted from the AFM force curves (retract) provides direct insights on the interfacial energy associated with the molecular arrangement of the SLI.

I will discuss the presence of adhesion force inhomogeneities on the SLI when a (111) textured polycrystalline gold electrode is immersed in 10mM of sodium sulphate solution. We observe the presence of potential-induced hysteresis of adhesion forces as the potentials are cycled from low to high values and back. Additionally, increasing the ionic concentration of the electrolyte, reduces the adhesion hysteresis. Under applied anodic potentials the sulphate anions in the electrolyte adsorb on gold electrode, which leads to a substantial increase in the interfacial adhesion forces. A force minimum is observed before the onset of sulphate adsorption, which we attribute to the point of zero charge as the surface charge switches from negative to positive.

We also identify a negative correlation of electrode grain curvature and its mean adhesion force, highlighting the role of solid electrode asperities in influencing the interfacial energy of the SLI. The grain curvature also dictates the potential-dependent adhesion response of any individual grain at applied potentials; the flatter grain the higher is their adhesion response. Furthermore, we observe adhesion force inhomogeneities at the single grain level, characterized by two distinct surface states that exhibit similar potential-dependent responses.

Our work demonstrates the use of EC-AFM as a multimodal technique that can probe SLI arrangement in-operando with nanoscale resolution. This work opens the door to future work probing of the solid-liquid interface in the presence of different types of (non-)specifically adsorbing anions and cations, as well as studying the dynamics of EDL formation via measuring adhesion forces at applied potential pulses.

Fuel cells and electrolyzers require electrocatalysts to minimize losses during energy conversion processes. It is common practice that researchers rely solely on electrochemical methods to test stability in search of novel electrocatalysts. While degradation can be tracked using such methods, they fail when one aims to understand governing degradation mechanisms responsible for the losses in catalyst performance. Complementary physicochemical techniques are required. One such technique is inductively coupled plasma mass spectrometry (ICP-MS) – the main topic of my talk.

ICP-MS is commonly used as a quality control tool, e.g., to confirm if a desired alloy composition is obtained during synthesis. Recently, ICP-MS has been increasingly involved in electrocatalysis research, e.g., checking electrolytes from batch cells on the presence of dissolved species. However, this technique's potential is revealed when ICP-MS is directly connected to an electrochemical cell – online or in-situ ICP-MS. This tool provides time- and potential-resolved analysis of electrocatalyst corrosion during electrochemical tests.

Since ICP-MS is still a somewhat less known technique in catalysis research, my talk will start with a brief introduction to this analytical chemistry tool. Main operational principles and their importance when coupling ICP-MS to an electrochemical cell will be discussed. Existing approaches to couple electrochemistry to ICP-MS will be briefly overviewed. To demonstrate how scientists can benefit from employing online ICP-MS in their research, representative examples from the author's works will be presented, including the dissolution of Pt in fuel cells and Ir in water electrolyzers. The talk will be summarized by showing how in-situ ICP-MS can be implemented in modern automated and autonomous electrocatalysis research.

The distribution of active sites is ubiquitous in many natural and industrial processes, due to the diverse physical or chemical features on an interface discernible only at the local level. However, a comprehensive understanding remains elusive due to the challenge of probing micro/nanoscopic regions and extracting and adequate statistical interpretation of the interfacial phenomenon. Moreover, the electrochemical response is generally recorded taken from macroscopic areas, which are then correlated with surface characterization obtained on a vastly different scale (~μm2), which is not necessarily representative of the macroscopic surface. This discrepancy may arise from the inadequate assessment of active site distributions, further complicating the interpretation of electrochemical data. Furthermore, it has been shown that the electrochemical magnitudes are also distributed at the micro/nanoscopic scale, contingent on the nature of the substrate [1,2]. Consequently, a more robust approach is warranted, utilizing techniques like scanning probe methods, which offer high spatial-temporal resolution, or in-situ techniques providing real-time insights into dynamic nanoscale processes.

In this work, we have employed Scanning Electrochemical Cell Microscopy (SECCM) as a powerful and versatile scanning probe technique, capable of surveying the surface with high spatial-temporal resolution, by independently probing hundreds of different surfaces, providing a novel perspective and insights into the activity distribution and role of the substrate state for the synthesis of nanostructures. Instead of relying on the response of a single region for interpretation, which may not offer a comprehensive representation, we emphasize the significance of acknowledging the diversity at the microscopic scale by summarizing the electrochemical profiles with statistical measures and observing their temporal- or potential-dependent evolution. This local approach offers a new perspective on interfacial phenomena, justifying the need for high-throughput experimentation and data-driven analysis. By combining the local electrochemical information with other imaging methods, such as Scanning Electron Microscopy (SEM), that can be co-located with the same area on the same scale, we can establish unambiguous correlations and a more complete understanding of the electrochemical response at the local scale. This so-called multi-microscopy approach facilitates studying the relationship between physicochemical features of a substrate and nanostructures, fundamental for relating microscopic events to macroscopic properties of new deposits. This understanding is the bridge connecting the microscopic world to macroscopic outcomes, shedding light on how surface heterogeneities influence reaction rates and nanostructure properties. Our multi-microscopy strategy, using data-driven high throughput local investigation to bring a new perspective to old phenomena, could be easily replicated for different interfacial phenomena such as electrocatalysis, phase growth, or corrosion [3,4].

In-situ techniques play an important role in gaining real-time insights into dynamic processes at the nanoscale. Employing a specialized TEM holder and chips, the electrochemical TEM (EC-TEM) setup allows for the direct observation of (nano)materials undergoing electrochemical reactions within their confined environments. This dynamic characterization enables the tracking of structural changes, such as phase transformations and morphological evolution.^[1,2] In our research, we studied the electrochemical growth of Cu on a GC electrode, as a model system.

While the in-situ characterization offers a new avenue of opportunities, it also comes with specific challenges that we need to overcome, such as the confined environment of the EC-TEM holder, and the beam-related effect. Moreover, nucleation and growth are especially sensible to the surface state, which can end up in the formation of different structures. To consider this, we conducted a detailed analysis of the GC working electrode situated on the specialized TEM chip surface using a scanning probe technique, Scanning Electrochemical Cell Microscopy (SECCM). This technique allowed us to characterize the GC electrochemical activity within a few micrometers, which, for the case of GC, have been shown before to be heterogenous.^[1,3] Overall, performing an extensive characterization of the electrochemical response of the TEM chips, in both in-situ and ex-situ conditions, allows us to better understand the electrochemical processes under TEM imaging conditions. In the context of our work, this is of special interest for the better understanding the fundamentals of metal nucleation, growth and dissolution on/from glassy carbon electrodes. This knowledge is essential for the rationalized design of active and durable nanostructured electrocatalysts for a wide range of electrochemical energy conversion and storage technologies.

Ensuring a sustainable future and reducing carbon emissions heavily relies on renewable energy sources. These sources allow us to harness electrons to drive chemical reactions and store energy in the form of chemical bonds. However, the performance of current electrocatalytic processes needs significant improvement. 

Magnetic field effects on electrocatalysis have recently gained attention due to the substantial enhancement of the oxygen evolution reaction on ferromagnetic catalysts. In this context, it is crucial to carefully characterize how magnetic fields affect mass transfer of charged reactants and products at the interfacial level, a phenomenon that occurs even on non-magnetic electrodes and is often overlooked.

In this talk, I will highlight the use of unconventional strategies to achieve spin control of reaction pathways on the surface of a catalyst.  By decoupling the effects involved in global (interfacial) vs local magnetic enhancement using in situ techniques,  I will provide a versatile strategy that can be easily implemented to boost electrocatalytic reactions across diverse materials. 

Structural characterization of an electrocatalyst under operando conditions is a prerequisite for fully understanding its activity and stability. Surface X-ray Diffraction (SXRD) is a powerful tool to obtain such information due to its high surface sensitivity and the possibility to probe the electrode-electrolyte interface in a noninvasive manner, especially when employing high energy photons. Furthermore, SXRD can easily be combined with other, e.g. spectroscopy or microscopy, techniques to aqcuire complementary information within the same experiment. Here, I will show the application of SXRD for atomic scale structural characterization of single crystal model electrocatalysts. First, I present the evolution of a Pt(111) surface under oxidizing (oxygen evolution as well as oxygen reduction reaction) conditions in a combined rotating disk electrode (RDE) SXRD experiment [1]. These experiments resolve the complete oxidation of the surface layer near the onset of the oxygen evolution reaction and the surface stability during oxygen reduction. Similar studies were performed under hydrogen evolution conditions in strong alkaline media to study the electrode restructuring due to cathodic corrosion under operando conditions. I further show how coupling SXRD with other techniques such as infrared reflection absorption spectroscopy (IRRAS) or surface optical reflectance (SOR) provides insights in the oxidation of CO on Pt(111) [2] and the reconstruction of Au(111) [3], respectively. Finally, I will discuss the applicability of SXRD for studying model electrocatalysts beyond bulk single crystals. This is exemplified by the characterization of epitaxial Cu thin films under CO2 electroreduction conditions. 

Electrochemical nucleation and growth (EN&G) are the cornerstone for many (nano)material growth routes and the main factor limiting battery durability [1]. The in-depth experimental assessment of the process is very challenging due to the random nature of initiation events (nucleation), the heterogeneity of surfaces and the (very) fast kinetics across several length scales. For all that, our understanding of the mechanisms involved is inaccurate and incomplete [2]. On the other hand, electrochemical dissolution (ED) of nanostructured interfaces is the main cause of material degradation in exposed environments (corrosion) or energy conversion and storage devices. Dissolution is also affected by random initiation events, fast kinetics and surface heterogeneity. Hence, a complete picture of the (combination of) dissolution pathways taking place is also elusive.

To address these challenges, we combine Scanning Electrochemical Cell Microscopy (SECCM) and in-situ Electrochemical Transmission Electron Microscopy (EC-TEM).

On the one hand, we performed thousands of high-throughput local electrochemical measurements for the nucleation of Au and Cu on different surfaces such as glassy carbon (GC), ITO, and Pt [3-4], which we analyzed with a data-centric approach. In addition, the spatially resolved electrochemical characterization enables a one-to-one correlation between the electrochemical data and the local surface properties, which are evaluated by SEM in identical locations to where the local electrochemical measurements have been performed.

On the other hand, we use SECCM as a high throughput tool to collect ED activity from randomly probed locations where metal nanoparticles (NPs) are pre-deposited by different methods (electrodeposition, sputtering, drop casting, etc.). Taking gold NPs as a case study, we show that, in the presence of chloride and at certain potentials, NP dissolution events are separated in time and can be therefore monitored by SECCM as single NP dissolution events [3, 5]. Data science methods, previously applied in the group for the study of pitting corrosion in stainless steel [6, 7] have been here deployed to explore the very large datasets containing information of the dissolution of several thousands of NPs.

The analysis of the SECCM EN&G and ED datasets is leveraged to discuss mechanistic aspects of noble metal nucleation, growth and dissolution processes. In addition, we show how EC-TEM allows the study of the early-stage growth/dissolution dynamics of the metallic phase. Interestingly, these measurements corroborate that the nature of the events resolved by SECCM corresponds to the dissolution of individual NPs. The combination of high-throughput SECCM, EC-TEM and data-centric analysis opens new opportunities for the rational design (electrodeposition) of functional nanostructured materials and the evaluation of their durability under electrochemical polarization (resistance to electrodissolution).

CO₂ reduction reaction (CO₂R) in acidic media is one of the alternatives to overcome low carbon utilization efficiencies and energy penalties due to the carbonate formation in an alkaline/neutral environment. In acid electrolytes the hydrogen evolution reaction (HER) is kinetically more favorable, limiting the conversion of CO₂ in C₂₊ products. Modulating the reaction microenvironment at the catalyst-electrolyte interface with inorganic and organic components is a strategy to promote the reaction activity, selectivity, and stability [1-3]. Here, we report a CO₂R reaction environment modulation strategy consisting of a polymer heterojunction coating that (1) increases local CO₂ availability; (2) stabilizes CO₂ reaction intermediates, leading to a high *CO coverage and improved C-C coupling in acid; and (3) regulates local proton activity with dedicated functional groups – as demonstrated by a combination of operando Raman spectroscopy and electrochemical characterizations. The polymer-coated PTFE/copper electrodes achieve a multicarbon Faradaic efficiency of 60% at 300 mA cm⁻² in acidic media.

CO₂ electroreduction (CO2E) offers a path generate widely used chemicals using CO₂ waste and renewable electricity. The viability of CO2E requires further progress in combined performance metrics such as selectivity, current density, and carbon utilization (among others). This is challenged by the loss of CO₂ into carbonates in high pH systems. CO2E operation in acid is one strategy to overcome this loss process, as carbonate species would get locally regenerated into CO₂ in a high-density H⁺ environment. Unfortunately, this approach also promotes the undesired hydrogen evolution reaction (HER). Control over the local CO2E reaction environment, and ion species in the double layer, has been shown as a promising direction to address this challenge.^1–5 Here, we present a strategy that uses different ionomer coatings to modulate the local reaction environment. We perform mechanistic studies, including operando spectroscopies, to study how these affect the dynamics of key ion species and reaction intermediates over the catalyst surface, and correlate this with performance trends. The ionomer coated PTFE/Cu electrodes achieve a Faradaic Efficiency of 73±6% for CO₂ to C₂₊ at 400 mA/cm² using an acidic electrolyte. This approach opens new possibilities for optimizing CO₂ electroreduction processes and achieving higher selectivity for value-added products, contributing to the advancement of sustainable and efficient energy conversion technologies.

Renewable-powered electrochemical carbon dioxide (CO₂) reduction reaction (CO2R) offers an attractive approach for the generation of low-carbon footprint chemicals. CO2R in acid has emerged as a promising solution to overcome drawbacks of traditional CO2R alkaline electrolyzers, such as limited carbon efficiency, which can lead to low energy efficiencies. Ionic species in the electrolyte have proven crucial in CO2R.[1,2] Especially in acid, cations have been shown to be essential to enable CO2R.[3] The role of anions, on the other hand, has received less attention in this context. Further advances in the field rely on resolving the CO2R environment and the role of ionic species at increasing current densities, where CO2R onset takes place in acid (> 50 mA·cm^-2).[4] Herein, we study the role of anionic species by assessing the local CO2R reaction environment at high current densities (> 200 mA·cm^-2), using operando Surface Enhanced Raman Spectroscopy (SERS). We have done so by investigating the different adsorbed intermediates and anions at varying pHs using a copper catalyst and H₂SO₄/K₂SO₄ electrolyte. We correlated changes in selectivity with presence and stabilization of adsorbed species and CO2R intermediates, revealing the key dynamic role that anions play in the competition between CO2R, carbonate-loss-regeneration pathways, and the suppression of HER in acid. Our study shows the paramount importance of measuring these processes at high current densities, offering crucial insights for advancing in acid CO2R.

The recent IPCC report emphasizes the necessity of scenarios with negative carbon dioxide emissions to meet the 1.5°C Paris Agreement goal. This underscores the vital role of negative emission technologies (NETs) in complementing comprehensive decarbonization efforts. Various NETs, such as afforestation, biochar, bioenergy with carbon capture and storage, direct air carbon capture and storage (DACS), and soil carbon sequestration, have been proposed. However, achieving COP27 goals requires a rational combination of technologies, as no single NET alone is likely to suffice. Among NETs, electrical approaches have garnered attention for their convenience, efficiency, and safety, although the electrochemical route is still in an early stage of development.

Capturing CO2 from dilute sources, including flue gas and the atmosphere, is crucial for managing global emissions and advancing downstream storage and utilization efforts. Electrochemical carbon capture methods stand out for their high energy efficiency, decentralized operation, ambient reaction conditions, and compatibility with renewable electricity.

In this context, a robust electroDAC approach with switchable electroactive adsorption materials is urgently needed. Cu-based electrochemically mediated amine regeneration (EMAR) has shown promise for controlled, reversible complexation with CO2 capture amines in aqueous solutions based on stability and performance. However, uncertainties persist regarding the precise mechanisms of Cu2+/Cu interfacial chemistry, dynamic competitive interactions at the surface and in bulk, and potential degradation routes or parasitic faradaic currents.

To address these uncertainties, we propose a reversible system using an electrostatic charge transfer mechanism at the electrode interface for energy-efficient CO2 capture and release. Our study focuses on investigating the stability and reactivity of various Cu-based catalysts under different conditions, employing spectroelectrochemical analysis to elucidate in-situ changes and interactions between adsorbed species and CO2 at the electrode interface.

Tuning the electrode-electrolyte interfaces via cations, pH, and concentrations is a widely accepted method for tuning the product selectivity of electrochemical carbon dioxide reduction (CO2R) reaction in aqueous media. However, the role of the interfacial water remains an unsolved puzzle to date.  Being a polar molecule, the water interacts either via the hydrogen end for cathodic reactions or via the oxygen end for anodic reactions by H-bonding or other chemical interactions to the electrode surface. In the electrode-electrolyte interface, water remains in mainly three forms: four H- H-bonded water (4-HB‧ H₂O), three H-bonded water (3-HB‧ H₂O), and free water (0-HB‧ H₂O). Depending on the no of H-bonded water, the activation energy trend is 4-HB‧ H₂O > 3-HB‧ H₂O > 0-HB‧ H₂O.[1,2] Presence of more rigid water (4-HB‧ H₂O) in the electrode-electrolyte interface decreases the competing hydrogen evolution reaction (HER) [3] at the same time decreases the accessibility of CO₂ to the catalytic surfaces impeding CO2R. [4] To explain this anomaly, we have employed in situ surface-enhanced Raman spectroscopy (SERS) to correlate the interfacial water structure with CO2RR product selectivity under higher current density using Cu as model catalyst varying the pH, concentration, cations, and anions of the electrolyte. The role of the interfacial pH, intermediate species specially adsorbed CO₂, competition between carbonate/bicarbonate formation, and adsorbed hydroxide (*OH) are also explored.

Stability and catalytic activity of metal oxides for the water oxidation at an electrolyzer anode are linked through the reactivity of oxygen atoms: metal–oxygen bonds are formed and broken during the electrocatalytic cycle, and metal–oxygen bonds are also what holds the material together. One way to probe this interplay is by isotope labelling of the oxygen in the electrocatalyst with ¹⁸O and determining by electrochemistry – mass spectrometry (EC-MS) whether this labelled oxygen is incorporated into the O₂ released. Through our work with chip EC-MS on sputter-deposited ¹⁸O-labelled oxides of Ru and Ir, we show the importance of quantitative and transparent data analysis in such oxygen-tracking experiments and their limitations. We then expand on the concept using CO oxidation, showing how the incorporation of labelled oxygen into the product CO₂ probes the reactivity of pre-catalytic surface states. A more direct probe of these states is to observe them spectroscopically. We show through fitting the UV-vis spectra of iridium oxide as a function of potential that the pre-catalytic redox transitions follow Frumkin isotherms, and propose a way of quantifying the relative importance of chemical vs electrochemical driving force in the rate-determining step.

The electrocatalytic reduction of CO2 (CO2RR) into valuable base chemicals and fuels is a very complex reaction that depends on the intimate relation between catalyst structure and external reaction conditions.[1] Despite considerable progress over the past few years, it is evident that the precise identification of the active sites of the electrocatalyst under operation remains a challenge, which hinders the rational design and industrial application of advanced electrocatalysts for eCO2RR. For this purpose, in situ characterization techniques are required that probe the catalyst structure, from bulk to surface, with improved time and space resolution.

In this presentation, I will discuss how we deploy in situ time-resolved Raman spectroscopy (TR-SERS) and advanced in situsynchrotron-based X-ray scattering and spectroscopy techniques to investigate the electrocatalytic activation of CO2 and the dynamic chemical structure of the electrode surface.[2,3] We have combined TR-SERS with cyclic voltammetry, chronoamperometry and pulsed electrolysis to study the time- & potential-dependent behavior of the electrode surface and the adsorbed species.[4] Furthermore, we deployed TR-SERS mapping to elucidate spatiotemporal heterogeneities of copper electrodes at work.[5] Finally, we used in situ small- and wide-angle X-ray scattering to couple the dynamic structure of the electrocatalyst to the performance for well-defined copper oxide nanoparticle electrodes.

References

[1] S. Nitopi et al. Chem. Rev. 2019, 119, 7610.

[2] H. An et al. Angew. Chem. Int. Ed. 2021, 60, 16576.

[3] S. Yang et al. Nat. Catal 2023, 6, 796.

[4] J. de Ruiter et al. J. Am. Chem. Soc. 2022, 144, 15047.

[5] H. An, J. de Ruiter et al. JACS Au 2023, 3, 1890.