Synergistic dual-functionality in acid: W-doped Ru for selective chlorine evolution and efficient hydrogen production

We propose a strategy of W doping to synergistically modulate the electronic structure and surface chemistry of Ru. • RuW 5% /CNT achieves a bifunctional breakthrough with HER and ClER in a unified strongly acidic medium. • Electron transfer from W to Ru downshifts the d-band center, optimizing H*/Cl* adsorption while suppressing O* adsorption. Hydrogen (H 2 ) is an important chemical in various chemical manufacturing industries. A promising method for the simultaneous production of H 2 and Cl 2 is the coupling of the cathodic hydrogen evolution reaction (HER) with the anodic chlorine evolution reaction (ClER) in an electrolyser using bifunctional electrocatalysts. In this study, a bifunctional catalyst (RuW 5% /CNT, W: 5 wt%) was designed. The catalyst was able to achieve a current density of 10 mA cm −2 in acidic HER with an overpotential of only 27 mV and a small Tafel slope with 21.5 mV dec −1 . Secondly, it was also electrochemically tested in ClER. The data showed that the overpotential of RuW 5% /CNT was 78.8 mV at a current density of 10 mA cm −2 , which was superior to that of the dimensionally stable anode (DSA). In addition, the cell voltage of RuW 5% /CNT||RuW 5% /CNT electrolyzer was only 1.626 V at a current density of 1 A cm −2 under HER and ClER coupling conditions, which provided an effective method for generating valuable chemicals. Theory calculations attribute this superior performance to the electronic modulation of Ru by W, which fine-tunes the adsorption strength of key reaction intermediates, offering a mechanistic foundation for the observed bifunctionality.