One-Dimensional Single-Chain Nb2Se9 as Efficient Electrocatalyst for Hydrogen Evolution Reaction

Abstract

In recent years, one-dimensional (1D) transition-metal chalcogenide nanowires have been considered as potential candidates to replace noble-metal-based electrocatalyst in water electrolysis because they exhibit high surface area and have plenty of exposed chalcogen atoms to act as active sites. Herein, we report the fabrication of the noble metal-free electrocatalyst of selenium-rich 1D single-chain niobium selenide (Nb2Se9) for efficient hydrogen evolution reaction (HER). The Nb2Se9 electrocatalyst is simply prepared by the filtration of dispersed Nb2Se9 in isopropanol through porous carbon paper used as a filter and electrode, which enables the fabrication of a binder-free electrocatalyst. HER activity is gradually increased with reduction in the bundle size of nanowire due to the increment of active sites where the selenium atoms are more exposed, eventually reaching a low onset potential of -27 mV, Tafel slope of 63.7 mV dec(-1), and a large exchange current density of 0.25 mA cm(-2) as well as a high hydrogen turnover frequency of (similar to 2 H-2 s(-1)) at -0.2 V. Furthermore, the remarkably stable structure of Nb2Se9 demonstrates the considerable importance of the stability and cyclic durability of the catalyst in acidic medium for practical application. To probe into the catalytic active sites of Nb2Se9 for HER, density functional calculations are performed, revealing that the selenium-rich site in Nb2Se9 serves as the primary active site for HER.