The electrochemical reduction of carbon dioxide (CO₂RR) to syngas (CO + H₂) presents a compelling strategy for defossilizing the chemical industry and advancing a circular carbon economy. However, integrating CO₂RR with downstream thermochemical processes remains a significant operational challenge [1,2]. Conventional strategies for generating ratio-tunable syngas rely heavily on modifying the catalyst composition or crystal structure during the initial synthesis stage, which restricts real-time operational flexibility and requires entirely different catalytic platforms for different target chemical outputs [3]. As underscored in our recent co‑authored collaborative review on low-temperature electrolysis scale-up, achieving on‑demand selectivity control without altering the underlying reactor architecture or catalyst configuration is essential for practical industrial deployment [2].

To address this challenge, the present work proposes a straightforward in situ activation strategy that dynamically modulates the syngas composition on a single bimetallic Cu₂O/ZnO catalyst [4]. By implementing brief potential-cycling treatments immediately before electrolysis under identical operational reaction conditions, the competitive balance between CO₂RR and the parasitic hydrogen evolution reaction (HER) can be systematically controlled [4]. Under a constant operational bias of -1.0 V_RHE, the developed catalyst yields distinct, highly stable H₂/CO molar ratios that depend entirely on the direction and polarization of the transient conditioning steps [4].

Importantly, the resulting syngas streams can be tuned to meet specific industrial benchmarks, providing a versatile interface for diverse downstream C1 chemical processing loops. The pristine, non-conditioned catalyst delivers an intermediate H₂/CO ratio of 2.5, which serves as an ideal feedstock for thermochemical methanol synthesis or Fischer-Tropsch synthesis of long‑chain hydrocarbons. When subjected to a potential cycling initiated from the anodic scan (AS), the catalyst promotes CO₂RR over water reduction, lowering the H₂/CO ratio to 0.7. This CO-rich output is perfectly tailored for industrial hydroformylation to produce valuable aldehydes and oxygenated monomers. Conversely, applying a potential cycling initiated from the cathodic scan (CS) suppresses surface defects and favors the HER, driving the H₂/CO ratio up to 5.0. This H₂-rich composition matches the demanding stoichiometric requirements needed for downstream catalytic methane synthesis.

Comprehensive ex-situ characterization indicates that the activation protocols control critical parameters, namely the copper oxidation state, the strength of the Cu-Zn electronic interaction, and surface oxygen-vacancy density, which dictate CO₂ binding strength and govern final product distribution [4]. To gain a deeper understanding of these surface dynamics, current work focuses on implementing an operando spectroelectrochemical Raman configuration. This diagnostic step aims to track the real-time structural evolution of the inorganic catalyst components and the liquid-solid interface under operational bias. Targeted parameters include monitoring the reversible Cu₂O to Cu⁰ phase transformations, evaluating structural ZnO lattice modes, and tracking variations in local carbonate/bicarbonate interfacial equilibria. Correlating these fundamental spectral trends with Faradaic efficiencies will provide a practical roadmap for evaluating surface speciation and for assessing online product-stream tuning in future electrolyzer designs.