A novel noble-metal-free binary and ternary In2S3 photocatalyst with WC and "W-Mo auxiliary pairs" for highly-efficient visible-light hydrogen evolution

Herein, noble-metal-free In2S3-WC and In2S3-based photocatalysts with dual cocatalysts of flower-like MoS2 and bulk WC were synthesized through a facile solvothermal reaction. Electrochemical results indicated WC increased the interface conductance of photocatalyst and boosted the transference of photogenerated carriers. The optimal In2S3-WC show a hydrogen production rate of 128.11 mu mol.h(-1).g(-1), which is around 6 times higher than In2S3-1%Pt (20.73 mu mol.h(-1).g(-1)). The above results demonstrate commercial WC has a crucial impact of replacing precious metal and separating carriers. Morphology characterization exhibited hydrangea In2S3 and flower-like MoS2 were attached to bulk WC. Gratifyingly, photocurrent, impedance and photoluminescence results demonstrated MoS2 further effectively separated the photogenerated carriers. Remarkably, the higher hydrogen generation rate of 390.52 mu mol.h(-1).g(-1) obtained by the optimal ternary In2S3-WC-MoS2 composite was around 3 and 18 times higher than the optimal In2S3-WC and In2S3-1% Pt. The photocatalytic results demonstrated that "W-Mo auxiliary pairs" was a great efficient synergistic cocatalyst for In2S3 to increase active sites and improve e(-)-h(+) pairs separation for H-2 generation. Furthermore, a probable reaction mechanism of the enhanced photocatalytic H-2 generation was also proposed. This presented research provides an effective concept to design novel and efficient noble-metal-free photocatalyst with "W-Mo auxiliary pairs" for prominent H-2 generation activity. (C) 2021 Elsevier B.V. All rights reserved.