W@Ag dendrites as efficient and durable electrocatalyst for solar-to-CO conversion using scalable photovoltaic-electrochemical system

Abstract

The electrochemical conversion of CO2 into CO using solar energy is the most efficient technique for artificial photosynthesis. However, many challenges remain, including the realisation of large-scale systems with high current density and stability. Herein, we report a carbon-supported tungsten-seed-based 3D silver dendrite (W@AgD) catalyst with abundant nanograin boundaries that exhibit enhanced CO2 reduction (CO2R) performance and stability. In zero-gap CO2 electrolyzer, W@AgD showed outstanding catalytic activity with a maximum CO partial current density of 400 mA cm–2 and stable operation for 100 h at 150 mA cm–2. The 3D dendrites improve CO2 mass transfer, while the abundant grain boundaries drive the AgxCyOz layer near the surface after activation, leading to superior CO2R catalytic activity owing to the strong local electric fields. In a stand-alone photovoltaic-electrochemical system, we achieved a solar-to-CO efficiency (ηSTC) of 12.1 % at 1 A. Thus, the synthesized catalyst and system are suitable for efficient solar energy storage.