Defect engineering tuning electron structure of biphasic tungsten-based chalcogenide heterostructure improves its catalytic activity for hydrogen evolution and triiodide reduction

Abstract

The design and exploration of high-efficiency and low-cost electrode catalysts are of great significance to the development of novel energy conversion technologies. In this work, metal and nonmetal heteroatoms co-doped biphasic tungsten-based chalcogenide heterostructured catalyst (Co-WS2/P-WO2.9) with rich defects is successfully synthesized by a vulcanization technique. The electrocatalytic performance of WS2/WO3 in the hydrogen evolution reaction (HER) and triiodide reduction reaction is significantly enhanced by modifying and optimizing its electronic structure through a defect engineering strategy. As an electrocatalyst for HER, the optimized Co-WS2/P-WO2.9 exhibits a low overpotential at 10 mA cm−2 of 146 and 120 mV with small Tafel slopes of 86 and 74 mV dec−1 in alkaline and acidic electrolyte, respectively. In addition, a Co-WS2/P-WO2.9 assembled solar cell yields a short circuit current density of 15.85 mA cm−2, an open-circuit voltage of 0.74 V, a fill factor of 0.66, and a competitive power conversion efficiency (7.83%), which is comparable or higher than conventional Pt-based solar cell (16.02 mA cm−2, 0.70 V, 0.63, 7.14%). The formation of a heterostructure in Co-WS2/P-WO2.9 leads to the presence of a built-in electric field in the interfacial region between Co-WS2 and P-WO2.9, which leads to an increased open-circuit voltage from 0.70 V for Pt to 0.74 V for Co-WS2/P-WO2.9. This work can provide a technical support for developing high-performance heterostructured catalysts, which open up a way for improving catalytic performance of heterostructured catalysts in the field of electrocatalysis.