Single-Crystal Integrated Photoanodes Based on 4H-SiC Nanohole Arrays for Boosting Photoelectrochemical Water Splitting Activity.

Abstract

Photoelectrochemical (PEC) splitting of water into H2 and O2 by direct use of sunlight is an ideal strategy for the production of clean and renewable energy, which fundamentally relies on the exploration of advanced photoanodes with high performance. In the present work, we report that single-crystal integrated photoanodes, that is, 4H-SiC nanohole arrays (active materials) and SiC wafer substrate (current collector), are established into a totally single-crystal configuration without interfaces, which was based on a two-step electrochemical etching process. The as-fabricated SiC photoanode showed a rather low onset potential of -0.016 V vs reversible hydrogen electrode (RHE) and a high photocurrent density of 3.20 mA/cm2 vs RHE 1.23 V, which were both superior to those of all reported SiC ones. Furthermore, such a rationally designed photoanode exhibited a fast photoresponse, wide photoresponse wavelength range, and long-term stability, representing its overall excellent PEC performance.