VS4 microspheres with Abundant Sulfur Vacancies as Enhanced Electrocatalysts for Hydrogen Evolution Reaction

초록

The development of clean and renewable energy carrier is necessary owing to the tremendous devastation of the environment and exhaustion of fossil fuel resources [1]. Electrochemical water splitting, which consists of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), is a promising approach for sustainable hydrogen production. In the water electrolysis, an active electrocatalyst is required, which lowers the kinetic barrier to drive HER [2]. Transition metal-based sulfide materials have attracted wide attention and are regarded as promising HER electrocatalysts owing to their advantages such as low-cost, unique electronic structures, high electrocatalytic activities on the edge sites, and outstanding chemical stability [3]. Herein, vanadium tetrasulfide (VS4) microspheres were successfully synthesized by hydrothermal method and thermal reduction. The partial reduction treatment at hydrogen atmosphere leads to the formation of abundant sulfur vacancies in VS4. VS4 electrocatalyst with abundant sulfur vacancies shows outstanding electrochemical activity for HER with low onset potential and low Tafel slope in acidic condition. Moreover, long-term durability of defect rich VS4 is confirmed by chronoamperometric tests. Such an electrocatalytic performance is attributed to the abundant sulfur vacancies in VS4. The rich defects of sulfur in VS4 effectively adjust band gap and enhance intrinsic electronic conductivity, leading to an outstanding electrochemical activity for HER compared to pristine VS4.