Selenium-Rich Configuration and Amorphization for Synergistically Maximizing the Active-Center Amount of CoSe<sub>1+<i>x</i></sub> Nanodots toward Efficient Photocatalytic H<sub>2</sub> Evolution
Duoduo Gao, Binbin Zhao, Feng Chen, Huogen Yu, Jiajie Fan, Jiaguo Yu
Abstract
Transition-metal selenides have been evidenced to be promising candidates for efficient H2 evolution cocatalysts due to a similar Se–Hads (273 kJ/mol) bond energy to Pt–H (251 kJ/mol), while their H2 evolution activity is still limited by the insufficient exposure of active Se atoms. Herein, a synergic idea of selenium-rich configuration and amorphization was developed to construct selenium-rich amorphous CoSe1+x nanodots for maximum exposure of more hydrogen-production selenium sites. For this purpose, the selenium-rich amorphous CoSe1+x nanodots with an ultrasmall size (0.2–1 nm) and selenium-rich character can be resourcefully and uniformly grafted with a TiO2 photocatalyst via the facile photoinduced electron-reduction way. Photocatalytic results showed that the as-prepared selenium-rich a-CoSe1+x/TiO2(0.5 wt %) attains a maximal hydrogen production activity (3400 μmol h–1 g–1, AQE = 16.3%), which is significantly superior to those of crystalline c-CoSe/TiO2 and conventional amorphous a-CoSe/TiO2 samples by a factor of 3.2 and 1.6 times, respectively. The outstanding activity can be ascribed to the cooperation of accelerated photoinduced electron migration from TiO2 to a-CoSe1+x and rapid hydrogen evolution on the enriched active Se sites. Meaningfully, the selenium-rich a-CoSe1+x can also be employed as the general H2 evolution electron cocatalyst for CdS and g-C3N4 photocatalysts. This work sheds light on the ingenious design and construction of efficient and inexpensive active-site-rich cocatalysts for highly active photocatalytic materials.