Pt-Loaded MoO3 Nanorods as a Catalyst for Hydrogen Evolution and Oxygen Reduction Reactions in a Basic Medium

The development of cost-efficient and effective electrocatalysts is highly needed for hydrogen evolution and oxygen reduction reactions (HER/ORR) for commercializing electrolyzer and fuel cell technologies. Addressing the sluggishness of alkaline HER and ORR kinetics is the key concern for the commercialization of electrolyzers and fuel cells. Platinum (Pt) is the state-of-the-art catalyst for the HER and ORR in a base. However, decreasing Pt loading without sacrificing its performance is still the key challenge. In this report, low Pt-loaded MoO3 nanorods (Pt/MoO3) were prepared for hydrogen evolution and oxygen reduction reactions in a base. The optimized catalyst, Pt-20%/MoO3, shows a similar to 40.6 mV overpotential in reaching -10 mA/cm(2) current density with 54.3 mV/dec Tafel slope for the HER. The catalyst also shows good stability and a similar to 98% Faradic efficiency for hydrogen evolution. The catalyst also exhibited good ORR activity in the base. Pt-20%/MoO3 attains a high half-wave potential of similar to 0.87 V (RHE), a high onset potential of similar to 1.017 V (RHE), and a long-term lifetime for oxygen reduction reaction due to the synergistic interaction between Pt and MoO3. The catalyst exhibits better HER and ORR activities in comparison to Pt/C. Further, the rotating ring disk electrode (RRDE) measurements of the catalyst confirmed that the ORR reactions go through 4 e(-) transfer processes. The HO2- production was found to be <10% during ORR, which is lower than that of commercial Pt/C. The optimal Pt coverage on MoO3 nanorods and strong synergy between Pt and MoO3 in Pt-20%/MoO3 make it more effective compared to other synthesized catalysts. Therefore, this work offers valuable insight for designing low Pt-loaded electrocatalysts for use in electrolyzers, fuel cells, or other renewable energy devices.