Heterointerface Engineering of Pt Nanoparticles Confined on i-MXene for Efficient ORR and HER Catalysis

Platinum is known as the most efficient catalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). However, Pt catalysts still encounter high loading demands, poor atom utilization, and uncontrolled nanoparticle aggregation, which severely restrict their practical use. To address these issues, we designed a Pt-W1.33C hybrid catalyst with strong interfacial coupling between Pt nanoparticles and the vacancy-rich i-MXene, W1.33C matrix. This robust Pt-W1.33C interaction effectively restricts Pt overgrowth, producing uniformly dispersed nanoparticles with an average physical size of 3.1 nm. The results show that the modulated electronic structure facilitates electron transfer from W1.33C to neighboring Pt sites, which reduces the energy barriers of chemical reactions and enhances the intrinsic electrochemical catalytic activity of the hybridized catalysts. As a result, the Pt-W1.33C catalyst with low Pt loading achieves an ORR overpotential of 320 mV at 0.1 mA cm−2, an HER overpotential of 36 mV at 10 mA cm−2, and Tafel slopes of 66 and 27.8 mV dec−1 for ORR and HER, respectively. The enhanced ORR and HER performance of Pt-W1.33C can be attributed to the synergistic interplay between Pt and W1.33C, including the disordered stacking of W1.33C, high conductivity of W1.33C, high catalytic activity of Pt, and strong Pt-W1.33C interfacial coupling, which, together, optimize electronic interaction and active-site accessibility in the hybrid catalyst.