Immobilizing Ultralow Loading Platinum Nanoparticles onto MXene through Defect Engineering to Enhance the Activity of the Hydrogen Evolution Reaction

Developing low-cost, highly active, and durable electrocatalysts for the hydrogen evolution reaction (HER) in acidic medium is essential for achieving the large-scale utilization of proton exchange membrane water electrolyzers. It has been demonstrated that non-precious-metal electrocatalysts are unable to substitute the most efficient platinum in a short period. Consequently, the fabrication of Pt-based heterogeneous electrocatalysts with ultralow loading and ultrahigh Pt utilization efficiency becomes a practical approach. Herein, an approach is reported to immobilize ultralow loading (∼0.26 wt %) Pt NPs to Mo vacancies on the surface of Mo 2 Ti 2 C 3 T x MXene. Because of the anchoring by Mo vacancies and the vast surface area of MXene, defect enriched Mo 2 Ti 2 C 3 T x supported Pt nanoparticles (Pt NPs/d-Mo 2 Ti 2 C 3 T x ) possess ultrasmall particle sizes (∼2.1 nm) and increased dispersity of Pt NPs. As a result, the as-prepared Pt NPs/d-Mo 2 Ti 2 C 3 T x reaches a current density 100 mA cm –2 at an overpotential of 123 mV. When compared to Pt/C (20 wt %), the mass activity of Pt on Pt NPs/d-Mo 2 Ti 2 C 3 T x is found to be 134 times higher. Meanwhile, it presents a high turnover frequency (8.49 H 2 s –1 at overpotential of 50 mV) and fast kinetics (a Tafel slope of 30.1 mV dec –1 ) as well as high durability (maintaining the current density of 100 mA cm –2 for more than 15 h). Theoretical simulations reveal that transferring electrons from Mo atoms regulated the d-band electronic structure of Pt NPs, resulting in a stronger interaction with adsorbed H species and ultimately boosting the HER activity.