Abstract:
The continuous consumption of traditional fossil energy exacerbates the energy crisis and environmental problems, and the development of clean and renewable energy is regarded as an urgent global challenge. Hydrogen, as a high-energy-density and sustainable energy carrier, is witnessing an increasing demand. Among various hydrogen production technologies, water electrolysis for hydrogen production is considered the most promising pathway because it can be coupled with renewable energy and is characterized by cleanliness and sustainability. In particular, proton exchange membrane (PEM) water electrolysis technology is widely noted for its advantages of high efficiency, fast response, and high gas purity; however, stringent requirements are imposed on the oxygen evolution reaction (OER) catalyst by the strongly acidic environment at the anode. RuO
2 is commonly employed as a catalyst in PEM water electrolysis. Nevertheless, under high voltage, RuO
2 is readily oxidized to soluble Ru species (Ru
n+,
n>4), whereby structural deactivation is induced and its long-term stability is compromised. To address this issue, a heteroatom doping strategy is developed, by which the performance of RuO
2 is enhanced through Ce doping. A series of composite electrode materials with different Ru/Ce ratios (Ce
x-Ru
yO
2/CP) are fabricated on carbon paper (CP) via a drop-coating and annealing method, and their catalytic performance and stability for the acidic OER are systematically investigated in 0.5 mol/L H
2SO
4. The morphology and phase structure of the materials are revealed by SEM and XRD characterization, respectively. Electrochemical tests demonstrate that superior catalytic activity is exhibited by the Ce
0.1-Ru
0.9O
2/CP material compared with RuO
2/CP. Overpotentials of 238 mV and 342 mV are achieved at current densities of 10 mA/cm
2 and 100 mA/cm
2, respectively, which are significantly lower than those of RuO
2/CP (270 mV and 370 mV). Moreover, a higher electrochemical active surface area and a lower charge transfer resistance are observed for Ce
0.1-Ru
0.9O
2/CP, indicating more favorable reaction kinetics. Stability tests confirm that stable operation for over 200 h is maintained by the catalyst at 10 mA/cm
2. It is verified that Ce doping effectively enhances the OER activity and stability of RuO
2-based catalysts in acidic media, and an effective reference is thereby provided for the development of efficient and stable anode catalysts for PEM water electrolysis.