Enhancing the Performance of Bi₂S₃ in Electrocatalytic and Supercapacitor Applications by Controlling Lattice Strain

Abstract Lattice‐strained Bi₂S₃ with 3D hierarchical structures are prepared through a top‐down route by a topotactic transformation. High‐resolution transmission electron microscopy and X‐ray diffraction (XRD) confirm the lattice spacing is expanded by prolonged sulfuration. Performance studies demonstrate that Bi₂S₃ with the largest lattice expansion (Bi₂S₃‐9.7%, where 9.7% represents the lattice expansion) exhibits a greater electrocatalytic hydrogen evolution reaction (HER) activity compared to Bi₂S₃ and Bi₂S₃‐3.2%. Density functional theory calculations reveal the expansion of the lattice spacing reduces the bandwidth and upshifts the band center of the Bi 3d orbits, facilitating electron exchange with the S 2p orbits. The resultant intrinsic electronic configuration exhibits favorable H* adsorption kinetics and a reduced energy barrier for water dissociation in hydrogen evolution. Operando Raman and post‐mortem characterizations using XRD and X‐ray photoelectron spectroscopy reveal the generation of pseudo‐amorphous Bi at the edge of Bi₂S₃ nanorods of the sample with lattice strain during HER, yielding Bi₂S₃‐9.7%‐A. It is worth noting when Bi₂S₃‐9.7%‐A is assembled as a positive electrode in an asymmetric supercapacitor, its performance is greatly superior to that of the same device formed using pristine Bi₂S₃‐9.7%. The as‐prepared Bi₂S₃‐9.7%‐A//activated carbon asymmetric supercapacitor achieves a high specific capacitance of 307.4 F g⁻¹ at 1 A g⁻¹, exhibiting high retention of 84.1% after 10 000 cycles.