The study of the effects of grain size, orientation and dislocation density on the HER performance of copper catalysts

Abstract

Utilizing multi-pass friction stir processing with recirculating water cooling, pure copper plates were processed to successfully synthesize catalysts with distinct grain sizes. An exhaustive investigation into their intrinsic structures and properties was conducted. Analyses using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) revealed that Cu-4.85 exhibits a preferred (111) crystallographic orientation along with a high dislocation density. Transmission electron microscopy (TEM) images clearly identified the types of dislocations present within Cu-4.85. Density functional theory (DFT) calculations further demonstrated that Cu-4.85 displays lower Gibbs free energy at the hollow site on the (111) plane, thereby facilitating the H* adsorption process. Collectively, this study delves into the cooperative influence of grain size, crystal orientation and dislocation density on the electrocatalytic hydrogen evolution (HER) performance. It was found that Cu-4.85 demonstrates exceptional HER activity, characterized by a reduced overpotential and a low Tafel slope. The study elucidates the mechanism of H atom adsorption in Cu-4.85 during the HER process, furnishing theoretical foundations for enhancing HER catalytic performance and offering significant theoretical and experimental insights for the design and fabrication of copper catalytic electrodes.