Construction of a carbon nanotube with Ru and Ni nanoparticles inside and externally loaded with a CeO2/RuO2 heterojunction as a bifunctional electrocatalyst for efficient water splitting in acidic media

Fabricated a novel CNT catalyst with Ru,Ni nanoparticles encapsulated inside and CeO 2 /RuO 2 heterojunctions outside. • Achieved lower OER/HER overpotentials of 163.9/105.8 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 electrolyte. • Interfacial electron transfer of CeO 2 /RuO 2 heterojunction effectively inhibits Ru overoxidation and dissolution. • Exhibits outstanding bifunctional electrocatalytic performance in both acidic and alkaline water splitting. Proton exchange membrane (PEM) water electrolysis links renewable energy surplus utilization to hydrogen storage—a critical connection enabled by its rapid adaptation to renewable power output swings. Nevertheless, developing bifunctional electrocatalysts incorporating high activity, economic feasibility, and long-term stability remains insufficient for fluctuation-adapted acidic electrolyzers. Herein, we designed and synthesized a bifunctional electrocatalyst (denoted as CeO 2 /RuO 2 /Ru,Ni@CNT), in which Ru and Ni nanoparticles are encapsulated within carbon nanotubes, while CeO 2 /RuO 2 heterojunctions are distributed on the exterior surface. The catalyst was prepared via a combination of calcination, hydrothermal, and annealing processes. Experimental results show the catalyst has excellent bifunctional activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 , with overpotentials as low as 163.9 mV (OER) and 105 mV (HER) at 10 mA cm −2 and good stability. The superior performance stems from the synergistic interactions of multiple factors, including the high dispersion and electrical conductivity of carbon nanotubes, the electronic modulation imparted by internal Ru and Ni nanoparticles, and the interfacial electron transfer at the CeO 2 /RuO 2 heterojunctions. This study establishes a new design direction for high-performance bifunctional electrocatalysts, relying on encapsulation-heterojunction structures, for renewable-coupled acidic PEM electrolysis. Download: Download high-res image (693KB) Download: Download full-size image