An effective integrated Cu2O photocathode to boost photoelectrocatalytic CO2 conversion

The exploitation of high-performance photocathodes remains a key challenge to bring the feasibility of narrow bandgap semiconductors into fruition for efficient artificial photosynthesis. Herein, we show a highly efficient photocathode system consisting of a photonic crystal structure based on a cuprous oxide (Cu2O) semiconductor for good light harvesting, hole-transport layers (HTL: FeOOH) that mediate and stipulate interfacial charge transfer derection from Cu2O to FTO, and a polypyrrole (PPy) layer as a sequential multi-electron transfer agent for CO2 reduction. The integrated Cu2O photocathode exhibits a record CO yield of up to 46.17 mu mol h(-1) at -2.0 V vs. Ag/Ag+, which achieves a high half-cell solar to CO efficiency (eta(STC)) of 1.58% and delivers an optimal quantum efficiency of 3.08%, transcending most of the previous Cu2O based photocathodes. Moreover, the integrated photocathode systems exhibit 7 hours operational stability. This work could shed light on designing and constructing efficient photocathode architecture for enabling practical solar-driven CO2 reduction as a means of solar energy storage.

Automated summary

The challenge lies in exploiting high-performance photocathodes to make narrow bandgap semiconductors feasible for efficient artificial photosynthesis. This study presents a highly efficient photocathode system based on a cuprous oxide semiconductor with a photonic crystal structure for good light harvesting, hole-transport layers that mediate and stipulate interfacial charge transfer, and a polypyrrole layer as a sequential multi-electron transfer agent. The integrated Cu2O photocathode achieves a record CO yield, high half-cell solar to CO efficiency, and optimal quantum efficiency, surpassing previous Cu2O based photocathodes. Moreover, the system exhibits operational stability for 7 hours. This work could guide the design and construction of efficient photocathode architecture for solar-driven CO2 reduction as a means of solar energy storage.