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

Abstract 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 μmol·h-1·g-1, which is around 6 times higher than In2S3-1%Pt (20.73 μmol·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 μmol·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 H2 generation. Furthermore, a probable reaction mechanism of the enganced photocatalytic H2 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 H2 generation activity.