Enabling Efficient Oxygen Evolution via Anchoring\nCarbon-Layer-Confined RuO<sub><i>x</i></sub> on a Well-Matched\nSubstrate

Oxygen\nevolution reaction (OER) is a multistep proton-coupled four-electron\nprocess with sluggish kinetics, which seriously limits the hydrogen\nproduction efficiency, thus it is of great importance to develop an\nefficient and stable OER catalyst. In this study, a two-step differential\npyrolysis strategy is employed to design a three-dimensional porous\nmicrostructured material consisting of RuO<sub><i>x</i></sub> nanoparticles coated by a thin-layer carbon, where the active particles\nwere isolated in separate chambers and the RuO<sub><i>x</i></sub> nanoparticles mainly existed in the form of a heterogeneous\ninterface between RuO<sub>2</sub> and partial metallic Ru. The preparation\nparameters of the catalysts are optimized via combining transient\nand steady-state polarization properties, and the target catalyst\nCat-500–1.5<i>t</i> shows the best OER catalytic\nperformance after ca. 60 h of a chronopotentiometry test in an acidic\nmedium with a much smaller performance change than other samples.\nThe unique design of adopting a carbon layer to form separate reaction\nchambers largely mitigates the excessive oxidation loss of the active\ncomponents under strong oxidation potential. The suitability of the\ncatalyst with the loaded substrate and test media is explored, and\nin an acidic medium, the carbon paper is much better than the titanium\nfiber, while in an alkaline medium, the titanium fiber is obviously\nsuperior to the carbon paper. On both carbon paper and titanium fiber,\nthe performance in an alkaline medium outperforms that in an acidic\nmedium, and the possible reasons for the performance difference are\nanalyzed. Herein, to obtain the actual electrocatalytic performance,\nthe optimal design of the catalyst structure and matching suitable\nconductive substrate in a specific medium are quite necessary, which\nprovides a feasible strategy for the acquisition of efficient and\nstable electrocatalysts and the desirable presentation of performance.