Metal-Free Artificial Photosynthesis of Carbon Monoxide Using N-Doped ZnTe Nanorod Photocathode Decorated with N-Doped Carbon Electrocatalyst Layer

Abstract

An artificial photosynthesis system based on N-doped ZnTe nanorods decorated with an N-doped carbon electrocatalyst layer is fabricated via an all-solution process for the selective conversion of CO2 to CO. Substitutional N-doping into the ZnTe lattice decreases the bandgap slightly and improves the charge transfer characteristics, leading to enhanced photoelectrochemical activity. Remarkable N-doping effects are also demonstrated by the N-doped carbon layer that promotes selective CO2-to-CO conversion instead of undesired water-to-H2 reduction by providing active sites for CO2 adsorption and activation, even in the absence of metallic redox centers. The photocathode shows promising performance in photocurrent generation (−1.21 mA cm−2 at −0.11 VRHE), CO selectivity (dominant CO production of ≈72%), minor H2 reduction (≈20%), and stability (corrosion suppression). The metal-free electrocatalyst/photocatalyst combination prepared via a cost-effective solution process exhibits high performance due to synergistic effects between them, and thus may find application in practical solar fuel production.