Hierarchical Bi2S3@CoS2/MoS2 core-shelled microspheres as bifunctional electrode catalysts for efficient triiodide reduction and alkaline hydrogen evolution reactions

Abstract

The core-shelled structural electrocatalysts composed of multiple transition metal sulfides are of broad promise in diverse power conversion and storage techniques. Herein, we have employed a plausible strategy to synthesize a series of porous composite electrocatalytic materials with hierarchical architecture based on metal-organic framework (MOF) derivatives (Bi2S3 @CoS2/MoS2, CoS2/MoS2, and Bi2S3 @MoS2). Remarkably, by virtue of the huge specific surface area, unique surface appearance, and the synergistic effect of multi-metals, the catalyst exhibits excellent electrocatalytic performance as a bifunctional catalyst in dye-sensitized solar cells (DSSCs) and hydrogen evolution reactions (HERs). Herein, the quaternary Bi2S3 @CoS2/MoS2 microspheres exhibit remarkable merits in facilitating the regeneration of iodine redox pairs in DSSCs as well as improving hydrogen evolution activity concerning CoS2/MoS2 and Bi2S3 @MoS2 microspheres. Particularly, the DSSCs with Bi2S3 @CoS2/MoS2-based counter electrode performed superior power conversion efficiency (PCE) of 9.43 %, outperforming that of Pt (7.87 %). Besides, a low onset overpotential of 29.5 mV, small Tafel slope of 56.2 mV dec–1, and low overpotential of 94.7 mV at the current density of 10 mA cm–2 were delivered for Bi2S3 @CoS2/MoS2 as HERs electrocatalyst under alkaline environment.