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External fields are introduced to catalytic processes to improve catalytic activities. The light field effect plays an important role in electrocatalytic processes, but is not fully understood. Here we report a series of photo-coupled electrocatalysts for CO2 reduction by mimicking the structure of chlorophyll. The porphyrin-Au catalyst exhibits a high turnover frequency of 37,069 h-1 at -1.1 V and CO Faradaic efficiency (FE) of 94.2% at -0.9 V. Under visible light, the electrocatalyst reaches similar turnover frequency and FE with potential reduced by ~ 130 mV. Interestingly, the light-induced positive shifts of 20, 100, and 130 mV for porphyrin-Co, porphyrin-Cu, and porphyrin-Au electrocatalysts are consistent with their energy gaps of 0, 1.5, and 1.7 eV, respectively, suggesting the porphyrin not only serves as a ligand but also as a photoswitch to regulate electron transfer pathway to the metal center.

Highly active and robust eletcrocatalysts based on earth-abundant elements are desirable to generate hydrogen and oxygen as fuels from water sustainably to replace noble metal materials. Here we report an approach to synthesize porous hybrid nanostructures combining amorphous nickel-cobalt complexes with 1T phase molybdenum disulfide (MoS2) via hydrazine-induced phase transformation for water splitting. The hybrid nanostructures exhibit overpotentials of 70 mV for hydrogen evolution and 235 mV for oxygen evolution at 10 mA cm-2 with long-term stability, which have superior kinetics for hydrogen- and oxygen-evolution with Tafel slope values of 38.1 and 45.7 mV dec-1. Moreover, we achieve 10 mA cm-2 at a low voltage of 1.44 V for 48 h in basic media for overall water splitting. We propose that such performance is likely due to the complete transformation of MoS2 to metallic 1T phase, high porosity and stabilization effect of nickel-cobalt complexes on 1T phase MoS2.

Controlling the concentrations of H2O and CO2 at the reaction interface is crucial for achieving efficient electrochemical CO2 reduction. However, precise control of these variables during catalysis remains challenging, and the underlying mechanisms are not fully understood. Herein, guided by a multi-physics model, we demonstrate that tuning the local H2O/CO2 concentrations is achievable by thin polymer coatings on the catalyst surface. Beyond the often-explored hydrophobicity, polymer properties of gas permeability and water-uptake ability are even more critical for this purpose. With these insights, we achieve CO2 reduction on copper with Faradaic efficiency exceeding 87% towards multi-carbon products at a high current density of −2 A cm−2. Encouraging cathodic energy efficiency (>50%) is also observed at this high current density due to the substantially reduced cathodic potential. Additionally, we demonstrate stable CO2 reduction for over 150 h at practically relevant current densities owning to the robust reaction interface. Moreover, this strategy has been extended to membrane electrode assemblies and other catalysts for CO2 reduction. Our findings underscore the significance of fine-tuning the local H2O/CO2 balance for future CO2 reduction applications. While challenging, controlling H2O/CO2 concentrations at the reaction interface is critical for achieving efficient electrochemical CO2 reduction. This work demonstrates that polymer coatings on the catalyst surface can effectively tune local H2O/CO2 concentrations, leading to selective, energy efficient and robust CO2 electroreduction. [ABSTRACT FROM AUTHOR]