Carbon capture, conversion and utilization (CCU) is gaining attention from the worldwide community for its ability to minimize CO2 accumulation in the atmosphere. Electroreduction of CO2 (eR-CO2) in combination with renewable electricity sources can be one of routes to achieve the target. Economic viability of eR-CO2 relies on improved performance accompanied with scalable system design. Membranes are commonly used for the separation of reduction and oxidation products as well as to provide a suitable micro-environment for CO2R. Commercial membranes often address only one of the key challenges in CO2R: either they offer suitable micro-environment for CO2R (e.g., anion exchange membrane) or suppress carbonate cross-over (e.g., cation exchange membrane and bipolar membrane). Here, we present a cation-infused ultrathin (~3 µm) solid polymer electrolyte (CISPE) that concomitantly addresses both of these challenges via bidirectional ion transport mechanism and suppressed anolyte diffusion. The CISPE was directly deposited into the copper cathode catalyst, eliminating the requirement of a standalone membrane. Our demonstrated system offers high selectivity towards CO2 electrolysis (~90%) and a single-pass CO2 utilization of ~18% at 200 mA/cm2 with the primary product being ethylene (faradaic efficiency of 65%). Our directly-deposited CISPE enabled record low energy consumption of 294 GJ/ton C2H4 along with ~110 hours of stable operation with C2H4 as the primary product. The present work offers a versatile design paradigm for functional polymer electrolyte, opening doors towards stable, and efficient electrolysis for high-value feedstock chemicals and fuels production using low-cost catalysts.

Rising atmospheric carbon dioxide (CO₂) levels have motivated the development of alternative chemical production technologies to reduce emissions. The electrochemical CO₂ reduction reaction (CO2RR) is one of several promising strategies that have been proposed for the utilization of CO₂. Through CO2RR, CO₂ can be converted into renewable fuels and valuable chemical feedstocks using clean electricity as an input. Of the possible CO2RR productions, multicarbon hydrocarbons and oxygenates, such as ethylene and ethanol, are promising commercial targets due to their large market sizes and high potential impact for emissions reduction.

CERT Systems Inc. is a carbontech start-up focused on the development of CO2RR to multicarbon product technology. Here we present an overview of CERT’s scale up journey through the NRG COSIA Carbon XPRIZE, a $20M global competition to develop and scale CO₂ utilization technologies. We will summarize the scale up process from the laboratory to CERT’s pilot demonstration during the finals of the competition. The key learnings and challenges of scaling up CO2RR to multicarbon products will be discussed. Finally, we will identify next steps for the technology and outlook for electrochemical CO₂ utilization.

Electrochemical power-to-gas and power-to-liquid technologies are promising chemical energy conversion approaches to be coupled with intermittent renewable energy sources to balance the grid while utilizing cheap excess energy at peak times. Production of CO from CO₂ reduction seems to be feasible even at pilot-scale, but the selective production of high-value multi-carbon products is challenging. CO reduction is a possible second step in the cascade electrochemical valorization of CO₂. Gas-phase electrolyzers offer a suitable platform for this process, but the low solubility of CO still poses notable challenges. This can be tackled by tailoring the microenvironment of the catalyst particles.

Here we demonstrate that a commercially available polymeric pore sealer can be used as catalyst binder, ensuring a high rate and selective CO reduction. Under optimal conditions, we achieved above 70% Faradaic efficiency for C2+ products formation at j = 500 mA cm⁻² current density. As no specific interaction between the polymer and the CO reactant was found, we attribute the stable and selective operation of the electrolyzer cell to the controlled wetting of the catalyst layer, due to the homogeneous polymer coating on the catalyst particles’ surface. These findings point out that polymers that form thin films on the catalyst surface (instead of forming nanoparticles that are incorporated among the catalyst particles, e.g., PTFE) might be suitable binders for CORR. In addition, sophistically designed surface modifiers are not necessarily required for CO electrolysis, hence the capital costs can be significantly decreased.

At the end of my talk I will discuss some general differences and similarities of electrochemical CO2 and CO conversion processes, mostly focusing on the role of the reaction environment, provided by the cell components and the cell architecture.

Energy- and cost-efficient CO₂ capture is of crucial importance for its subsequent viable utilization. Ionic liquids (ILs) have emerged as a promising material for reducing carbon dioxide emissions from large-scale sources due to their properties and versatility. ILs are considered green solvents with high thermal stability, tunable structure, low volatility, and a strong affinity for CO₂ molecules. These properties of ILs make them a potential alternative to amine-based CO₂ capture processes. The challenges of using ILs come with their high viscosity, which causes unfavorable transport barriers. Encapsulated ionic liquid has been proposed to overcome mass transfer limitations, increasing the contact between gas and liquid, and improving the mass transfer rate. This study showed the development of new materials, combining efficiency, safety, and sustainable processes. Water-based nanocapsules of Emim[BF4], using poly(ionic liquid) Poly(diallyldimethylammonium tetrafluoroborate) as shell, were successfully obtained by Nanospray dryer B-90. Capsules were characterized and have the potential for CO₂ capture evaluated. The combination of these promising materials showed great potential for CO₂ capture and CO₂/N₂ separation (53.4 mg CO₂/g; CO₂/N₂ selectivity: 4.58). Thermal stability and the regeneration of this material after successive sorption–desorption cycles were also successfully demonstrated, emphasizing this as a potential alternative.

Progressive replacement of fossil fuels by sustainable and renewable energy sources is one of the most actual contemporary challenges. In this context, the solar-based electroconversion of water has become a valuable concept for production of an alternative fuel based on “green” hydrogen generation. Transition metal nanoparticles, such as nickel, are the benchmark catalysts for hydrogen evolution reaction, since they are highly active, stable and earth-abundant.

One of the emerging fields of solar energy harvesting is enhancing the catalytic reaction through the local surface plasmon resonance (LSPR) effect of the catalyst. Most studied mechanisms of the energy transfer from plasmonic nanoparticles are based on hot electron injection and plasmon-induced resonant energy transfer. However, the photothermal effect of the plasmon in transition metal nanoparticles is still often considered detrimental and is severely underestimated in the literature.

In this work, we have synthetized Ni nanoparticles with an elongated average shape by wetness impregnation of the hard silica template. The high distribution of sizes results in a broad plasmonic absorption in the visible range, which leads to a significant photothermal effect under solar illumination, reaching 93°C after 5 min under incident power of 0.5 W cm^-2.

Irradiation of the Ni-NPs cathode with concentrated solar light under HER cathodic conditions leads to the increase of the hydrogen production up to 27%. On the other side, by applying galvanostatic conditions to the electrode we were able to decrease the overpotential needed for the hydrogen formation by 185 mV with negligibly small overall heating of the cell.

Pulsed illumination has resulted a three-staged electrochemical response to the illumination, reflecting i) breaking of the nickel/electrolyte equilibrium towards adsorption predominance, ii) blocking of the active sites and iii) establishing of the new balance between the electronic and ionic subsystems. The transient study revealed two main processes in the mechanism of light-induced reaction enhancement at low current densities: i) enhanced electron transfer due to strong plasmonic heating and ii) thermal energy dissipation from the electrode to the electrolyte.

Based on the obtained results, we have shown that the illumination of the nanostructured nickel catalyst with solar light can lead to the enhanced HER rate, and, as a result, to improved hydrogen production. We expect the LSPR photothermal approach to pave way to a more efficient photoelectrochemical water splitting process, taking advantage of visible and near-IR illumination.

The direct conversion of greenhouse gases into green fuels and valuable chemicals is of paramount interest to achieve a decarbonized future [1]. The use of carbon dioxide and methane are of special interest as they are the main greenhouse gases emitted from anthropogenic sources, commonly considered industrial waste. In terms of fundamental research, the electrochemical carbon dioxide reduction to valuable chemicals has achieved great progress in the last few decades. Notwithstanding, few advances have been achieved in the electrochemical oxidation of methane [2].

Direct electrochemical methane activation strategies focus on tuning the electrode surface structure and composition [2]. The materials selected for the partial oxidation of methane need to activate methane and stabilize the intermediates involved to avoid the formation of carbon dioxide. Theoretical studies have shown that metal oxides are promising catalysts for the direct electrochemical activation of methane through the water discharge mechanism [3]. According to theoretical calculations, iridium oxide (IrO_x) catalysts present a low overpotential for the oxygen evolution reaction (OER) and lower free energies of methane activation and *O formation compared to *OOH formation in the OER. Thus, these calculations suggest IrO_x should be an interesting catalyst for the electrochemical conversion of methane into methanol. However, the experimental work published in this regard is very limited [4].

In this presentation, we show the results we acquired on the electrochemical methane activation using an IrO_x surface as a catalyst in HClO₄ electrolyte. For this purpose, we used an Ir polycrystalline oxidized electrochemically. The results aim to bring further understanding of the methane activation using metal oxides and discuss the purposed mechanisms reported in the literature.

The chemical instability of hybrid halide perovskites in protic solvents remains the main obstacle for their application including solar fuels generation. In our work, we successfully stabilize 2D perovskite PEA₂PbI₄ in aqueous solutions of phenylethyl ammonium iodide (PEAI). XPS and XRD spectroscopy allow us to determine the 2D perovskite changes before and after the water immersion. Additionally, inductive coupled mass spectroscopy (ICP-MS) reveals the compositional changes of the electrolyte after 2D perovskite immersion. Photoelectrochemical characterization was used in a three electrode setup to measure photocatalytic activity of this material toward the hydrogen evolution reaction. Furthermore, IMPS/IMVS and impedance spectroscopy was implemented to characterize the photoelectrochemical process involved in this reaction. This result denotes the possibility to use layered perovskite absorbers for solar fuels generation in aqueous media, providing valuable information on the general understanding of the degradation of perovskites and opening an exciting window to novel applications of perovskite absorbers.

We report the use of a silver sputtered gas diffusion electrode (GDE) for electrochemical CO₂ reduction in a membrane electrode assembly and probe the factors affecting catalyst utilization at high current densities. Catalyst utilization is significantly affected by the gas flow channel design at the cathode which distributes the reactant to the catalyst sites. The high pressure drop present in a serpentine flow channel enables a partial current density of 205 mA/cm² for CO production at a cell voltage of 2.76V. Double layer capacitance measurements reveal significant differences in catalyst wetting between the flow patterns due to changes in pressure drop, salt precipitation at the cathode and reactant distribution at the surface of the GDE. Modelling of the gas flow channel and GDE reveals inhomogeneity in reactant distribution affecting catalyst utilization significantly. These findings can be used to formulate design rules for maximizing catalyst utilization in zero gap CO­₂ electrolyzers. 

Carbon dioxide (CO₂) capture and electrolysis is a promising route to produce valuable chemicals from CO₂. Coupling the capture and electrolysis has the potential to intensify the process and reduce the overall energy cost. Taking amine scrubbing process as an example, the CO₂ electrolysis can displace the energy-intensive amine recovery of the capture and produce valuable chemicals (e.g., carbon monoxide, CO) to offset the overall carbon abatement cost. Our recent process modelling results[1] found that the integrated route could save up to 42% overall energy if the integrated electrolysers perform similarly to the state-of-the-art gas-fed electrolyser. 

However, the reported integrated electrolysers show inferior performance to the gas-fed electrolysers. Understanding the catalytically active species for CO₂ conversion in the capture media is essential to rationally design an efficient integrated electrolysis system, but remains underexplored. This talk aims to uncover the dominant active species for the CO₂ conversion to CO in a commonly studied ethanolmaine aqueous capture medium from our recent experimental findings. We will first discuss the potential CO₂-related species available in the amines. The following part will show how the chemical species can change locally under CO₂ electrochemical conditioning, and discuss their role in determining CO₂-to-CO conversion efficiency. This talk will conclude with potential research directions that can further boost the performance of the integrated electrolysis.

The electrochemical partial oxidation of methane to methanol is a promising approach to the transformation of stranded methane resources into a high-value, easy-to-transport fuel and chemical. The direct transformation of methane to methanol in remote locations requires selective catalysts capable of operating at near ambient temperatures inside a modular device. Over the last decade, transition metal oxides have been shown as potential electrocatalysts for this transformation. However, a comprehensive and systematic study of the dependence of methane activation rates and methanol selectivity on catalyst morphology and experimental operating parameters during testing has not been realized.

In this contribution, we describe an electrochemical method for the deposition of a family of thin-film transition metal (oxy)hydroxides as catalysts for the partial oxidation of methane. CoO_x, NiO_x, MnO_x and CuO_x are discovered to be active for the partial oxidation of methane to methanol in a carbonate electrolyte. TiO_x and FeO_x oxides show no selectivity for methanol at the oxidative potentials tested. Taking CoO_x as a prototypical methane partial oxidation electrocatalyst, we systematically study the dependence of activity and methanol selectivity on catalyst film thickness, overpotential, temperature and electrochemical cell hydrodynamics in a gas-tight rotating cylinder electrode cell. Optimal conditions of low catalyst film thickness, intermediate overpotentials and intermediate temperatures are identified to favor methanol accumulation in the electrochemical cell. The rate of transport of methane and methanol in and out of the electrocatalyst surface is also shown to be an important design parameter for future methane to methanol electrochemical cells. Through a combination of control experiments and DFT calculations, we show that the oxidized form of the as-deposited (oxy)hydroxide catalyst films are active for the thermal oxidation of methane to methanol even without the application of a bias potential, demonstrating that high valence transition metal oxides are intrinsically active for the activation and oxidation of methane to methanol at ambient temperatures.

The conversion of biomass platforms to value-added chemicals represents an exciting opportunity to extract value from the anodic half reaction in water/CO₂ electrolysis while also holding the potential to lower the cell voltage required to carry out the full reaction.  Despite this promise, catalysts still do not exist that can operate at sufficiently low overpotentials with high rates and selectivity and a comprehensive understanding of many of these reactions is still lacking. Against this backdrop, my lab’s work in recent years has focused on the use of operando spectroscopy (carried out as the reaction progresses) to probe reactions such as the oxidation of hydroxymethylfurfural (HMF) to furandicarboxylic acid (FDCA). Further, we translate the insights gained into the rational design of next-generation catalysts with enhanced performance, thus creating an iterative feedback cycle. This talk will focus on research that spans from our first efforts on simple gold nanoparticles all the way to recent complex materials such as metal-organic frameworks (MOFs) that operate in unique ways to electrochemically convert biomass platforms to value-added products.

One promising technology to decarbonise our economy is to use carbon dioxide (CO2) from a point source or air as a starting feedstock to produce chemicals, while leveraging the rapidly-growing renewable energy as a driving force. Such an approach relies traditionally relies on separate capture and conversion processes. Both processes are energy costly and face their own technical challenges. For example, amine-based capture media requires a typical cost of US$50-150 to capture one tonne of CO2. The recovery of capture media (e.g., amines) and CO2 cost up to 90% of the overall energy for the capture process. Meanwhile, CO2 conversion by electrochemical processes takes substantial energy for the conversion, separation and electrolyte recovery steps.

As a means to reduce energy input and reduce implementation costs, coupling the capture and electrolysis conversions steps into an integrated process has been proposed. Here the conversion process uses the CO2-saturated capture media, instead of free gaseous CO2. The new integrated CO2 electrolysis process can then theoretically displace the energy-intensive amine regeneration of the capture and produce valuable chemicals (e.g., carbon monoxide) to offset the overall carbon abatement cost. However, at present the integrated electrolysers shows inferior performance to the gas-fed electrolysers. Hence, an important question needs to be answered: will the integrated capture and conversion route fulfill its promise to be more energy-efficient than the sequential route?

This talk attempts to answer this question by discussing our recent process energy system modelling results.[1] Firstly, our results find that the electrochemical CO2 conversion is the dominant energy contributor to the overall capture and conversion, and its energy cost must be minimized. If the integrated electrolysis process is of the same energy cost to the state-of-the-art gas-fed electrolyser, the integrated route could then save up to 42% energy as compared to sequential capture and conversion steps. However, this energy advantage quickly diminishes if future gas-fed electrolyser remains more energy efficient, or if bicarbonate formation in the gas-fed system is avoided. This talk will conclude with challenges and opportunities for the development of integrated capture and electrolysis.

Glycerol is a residue generated in biodiesel production that has a low economic value due to its overproduction. Recently, different oxidation processes have been developed for glycerol oxidization towards added value products such as dihydroxyacetone or formic acid, one of them being the photoelectrochemical route that improves the process efficiency using solar light. In this work we have synthetized and studied BiVO₄ and TiO₂ semiconductor electrodes with the objective of evaluating their activity as photocatalysts using different experimental conditions (electrolyte and pH). The studied support electrolytes are sodium sulphate and sodium phosphate at pH 2 and 7. The results show that in an acidic Na₂SO₄ 0,5 M medium the BiVO₄ electrode presents its maximum photocurrent and in a neutral Na₂SO₄ 0,5 M medium TiO₂ electrode reaches its best performance. It has been assessed that faradaic efficiencies towards glycerol oxidation follows an opposite trend to water oxidation, the latter being more favoured using TiO₂ than BiVO₄ electrodes. The oxidation product analysis by HPLC and H-NMR shows that BiVO₄ presents better faradaic efficiency for glycerol oxidation than TiO₂ but with a lower selectivity towards a given product. Furthermore, in all cases, it has been proved the beneficial role of illumination with respect to dark electrolysis. It has been observed that the use of phosphate ions as supporting electrolyte is harmful for the glycerol oxidation due to the peroxide generation, besides the instability of BiVO₄ in acidic phosphate electrolyte. On the contrary, using sulphate anions as the supporting electrolyte it has been achieved faradaic efficiencies over 80 % with a constant selectivity at different reaction times.

Electrochemical CO₂ reduction reaction (CO₂RR) holds promise for the conversion of green electricity (e.g., solar electricity) into fuels and CO₂ mitigation, to address the global warming issue. Biomass, on the other hand, is an abundant renewable energy resource with a potential to provide sustainable source of fuel. Nevertheless, CO₂RR suffers from high applied potential mainly due to the inefficient oxygen evolution reaction (OER) in the counter electrode, as well as low selectivity—impeding its commercialization; and the biomass upgrading process emits significant amount of greenhouse gases—hindering its employment. Here in this work, we first design and synthesize active and selective electrocatalysts for the CO₂ reduction and biomass oxidation. Combining these two reactions within one unified electrochemical system is proposed in literature to further decrease the total applied potential and improve the energy efficiency, however often the attained current density in biomass oxidation reactions (i.e., few mA/cm²) is not comparable to the commonly used OER and subsequently not suitable for the required current densities in CO₂RR systems (i.e., > 100 mA/cm²). Thus, in this work, we demonstrate a feasible approach to attain an energy efficient combined electrochemical system that works at current density > 100 mA/cm². In this talk, I will report some of our recent achievements in catalyst design for both reactions, their performance, energy efficiency improvements, and molecular understanding of the reaction mechanism. The talk will be mostly focused on CO₂RR to formate and methane, and hydroxymethylfurfural (HMF) oxidation to furandicarboxylic acid (FDCA).

Once solar fuels are accessible economically and widely, we need a device to convert them into useful energy. In this aspect, fuel cells (FCs) are more appealing than conventional internal combustion engine in terms of energy efficiency because of no entropy energy waste. However, mass deployment of FCs demands better electrode-electrolyte interfaces to catalyze oxygen reduction reaction (ORR, especially in acidic environments), the kinetics of which depends on the energetics of surface adsorption as well as on the electrolyte environment. While the former has been well established using experimental and theoretical work, the effect of the electrolyte remains relatively unexplored. In this talk, I will first show an unanticipated effect of nonspecifically adsorbing (NSA) anions on the ORR kinetics on a Pt(111) electrode in acid. The electrolyte-related trends do not follow the usual ORR descriptor, i.e. *OH binding energy. Instead, a new voltammetry-accessible descriptor, namely the reversibility of the *O↔*OH transition on the (111) terrace was proposed to successfully track the dependence of ORR rates on electrolyte properties, including the concentration/identity of NSA anions in acidic media, cations in alkaline media, and the effect of the presence of ionomers, as observed in this study and in the literature. An enhanced model that relates the ORR rate on Pt(111) to the rate of the *O to *OH transition, in addition to the traditional “thermodynamic” *OH binding energy descriptor, was established, suggesting that there is more than one descriptor for the overall ORR rate. Our updated picture of the ORR can help in rationalizing the different trends for the ORR rate on stepped Pt surfaces in acidic vs. alkaline media. This study paves an avenue towards a more complete understanding of the various factors that determine the ORR rate on Pt surfaces.