Fig. 4: In-situ characterization and electrochemical analysis of PtRuNi-Ox.

a Schematic diagram of in-situ Raman device. b The in-situ Raman spectra of PtRuNi-Ox during alkaline HER. c Bode plots and d the fitting Rct values of PtRuNi-Ox during HER in alkaline freshwater, respectively. e Bode plots and f the fitting Rct values of PtRuNi-Ox during HER in alkaline chemical wastewater, respectively. g Charge density variation in the PtRuNi alloy and oxide heterostructure model, where blue and yellow areas represent regions of electron accumulation and depletion, respectively. Calculated Gibbs free energy of (h) H* adsorption and i OH* adsorption at PtRuNi-Ox surface and interface site, respectively. j Schematic diagram of HER at PtRuNi-Ox interfaces.