Au-Modulated Z-Scheme CuPc/BiVO4 Nanosheet Heterojunctions toward Efficient CO2 Conversion under Wide-Visible-Light Irradiation

Abstract

Unraveling the sluggish charge separation, insufficient catalytic sites, and limited visible-light absorption for Z-scheme heterojunction photocatalysts still remains a great challenge toward CO2 conversion. Herein, ultrafine Au-modulated copper phthalocyanine/BiVO4 nanosheet heterojunctions (CuPc/Au-BVNS) with wide-visible-light responses have been successfully fabricated as efficient photocatalysts for CO2 conversion to CO, achieving 9-time and 35-time photoactivity improvement compared to pristine BVNS (ca. 5 nm) and the previously reported BiVO4 nanoflake (ca. 15 nm), respectively. The exceptional photoactivity is mainly attributed to the ultrafine Au interfacial modulation, which is well capable of inducing the directional electron migration of BVNS and the highly dispersed CuPc assembly with the increased loading amount, synergistically strengthening the Z-scheme charge transfer and separation mainly based on the surface photovoltage spectroscopy assisted with the monochromatic beam and electron paramagnetic resonance technique. Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy, CO2 temperature-programmed desorption measurement, and electrochemical results demonstrate that the central metal Cu2+ in the high-dispersion CuPc exhibits potential catalytic functions for CO2 reduction, much superior to other metals in MPc (M = Co and Ni)-modified ones. This work highlights the importance of strengthening artificial Z-scheme charge transfer and provides new strategies for designing BiVO4-based heterojunctions by controllably assembling MPc toward efficient solar-driven CO2 conversion.