Crystal Facet‐Controlled Efficient SnS Photocathodes for High Performance Bias‐Free Solar Water Splitting

• Published in: Advanced science Vol. 8; no. 21; pp. e2102458 - n/a
• Main Authors: Lee, Hyungsoo, Yang, Jin Wook, Tan, Jeiwan, Park, Jaemin, Shim, Sang Gi, Park, Young Sun, Yun, Juwon, Kim, Kyungmin, Jang, Ho Won, Moon, Jooho
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.11.2021; John Wiley and Sons Inc; Wiley
• Subjects: Efficiency; Electrodes; facet control; fast crystallization; Hydrogen; molecular ink; photoelectrochemical water splitting; Scanning electron microscopy; Semiconductors; SnS; Sulfur; tandem device
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202102458

To achieve a high solar‐to‐hydrogen (STH) conversion efficiency, delicate strategies toward high photocurrent together with sufficient onset potential should be developed. Herein, an SnS semiconductor is reported as a high‐performance photocathode. Use of proper sulfur precursor having weak dipole moment allows to obtain high‐quality dense SnS nanoplates with enlarged favorable crystallographic facet, while suppressing inevitable anisotropic growth. Furthermore, the introducing Ga2O3 layer between SnS and TiO2 in SnS photocathodes efficiently improves the charge transport kinetics without charge trapping. The SnS photocathode reveals the highest photocurrent density of 28 mA cm−2 at 0 V versus the reversible hydrogen electrode. Overall solar water splitting is demonstrated for the first time by combining the optimized SnS photocathode with a Mo:BiVO4 photoanode, achieving a STH efficiency of 1.7% and long‐term stability of 24 h. High performance and low‐cost SnS photocathode represent a promising new material in the field of photoelectrochemical solar water splitting. Crystal facet control dramatically enhances both the photocurrent density of SnS photocathodes to 28 mA cm−2 at 0 VRHE and the onset potential to 0.4 VRHE owing to the extended (101) facet. By combining the photocathode with a Mo:BiVO4 photoanode, unbiased solar water splitting is successfully demonstrated with bench‐mark efficiency (≈1.7%) and long‐term stability of 24 h.