Design Of Three-Dimensional Copper-Based Photoelectrode And Its Application In Artificial Photosynthesis

With the rapid growth of the world’s population and the continuous development of modern industry,the use of fossil energy and CO₂ emissions have been increasing year by year,causing environmental and climate problems such as desertification,rising sea levels,polar ice melting,and huge energy crises.Therefore,solving these issues is to achieve the resource utilization of CO₂ by converting it into value-added chemicals or fuels.Photoelectrocatalytic CO₂ reduction（PEC-CO₂RR）simulates photosynthesis in nature and is one of the most promising technologies for achieving CO₂ net-zero emissions through CO₂ resource utilization.The key to improving the efficiency of PEC-CO₂RR is to develop new and efficient photoelectrocatalytic materials.Copper oxide（Cu₂O）is a naturally-occurring p-type semiconductor material with a direct bandgap of 1.9-2.2 e V.Under AM 1.5G illumination,the theoretical maximum photocurrent density is 14.7 m A·cm^-2,making Cu₂O a promising p-type absorber material in photoelectrocatalytic systems.The suitable energy band position and copper active sites of Cu₂O are conducive to the CO₂ reduction reaction.However,as a photocathode,the low photocarrier separation efficiency of Cu₂O needs to be addressed by modification or structural design to improve the light absorption properties and photocarrier separation efficiency of photoelectrocatalytic materials.This paper focuses on Cu₂O as the main material,constructs a photonic crystal structure photoelectrocatalytic material based on a multi-step modification strategy.The photoelectrochemical properties and PEC-CO₂RR performance of the material are studied,proposing possible photo-generated carrier transfer paths.The research content of this paper includes the following two parts:（1）A photocathode with photonic crystal structure（Fe OOH@Cu₂O IO@PPy）was constructed with Fe OOH as the hole transport layer,polypyrrole（PPy）as the protective layer and electron transport layer.The research shows that Fe OOH as the hole transport layer promotes the transfer of photogenerated holes from Cu₂O to Fe OOH,and PPy as the protective layer significantly improves the stability of Cu₂O,inhibiting the recombination of photocarriers.The introduction of the photonic crystal structure effectively enhances the light absorption capacity,as verified by finite-difference time-domain（FDTD）simulation.The FCu P IO（Fe OOH@Cu₂O IO@PPy）was tested for CO₂ reduction and achieved a CO production rate of46.17μmol·h^-1 with a Faraday efficiency of over 99%at a bias potential of-2.19 V vs.Fc/Fc⁺.The use of a multi-layer modification strategy and the introduction of a photonic crystal structure significantly improved the PEC performance of Cu₂O.（2）A Z-Scheme heterojunction three-dimensional photonic crystal structure WAg Cu IO（WO₃@Ag@Cu₂O IO）and a control photocathode were constructed.Experimental results showed that the introduction of the photonic crystal structure in WAg Cu IO（WO₃@Ag@Cu₂O IO）led to significant absorption enhancement in the 400-600 nm range compared to WAg Cu（WO₃@Ag@Cu₂O）and Cu₂O.Thanks to the construction of the Z-Scheme heterojunction,WAg Cu IO obtained good photo-generated carrier separation performance,and the photonic crystal structure enhanced the light absorption for visible light.The photoelectrocatalytic performance achieved 29.35μmol·h^-1 CO production rate with 87.02%faradaic efficiency at-2.19 V vs.Fc/Fc⁺bias potential.The superior performances are ascribed to constructing the Z-Scheme heterojunction and introducing the photonic crystal structure.