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 Mo2Ti2C3Tx MXene. Because of the anchoring by Mo vacancies and the vast surface area of MXene, defect enriched Mo2Ti2C3Tx supported Pt nanoparticles (Pt NPs/d-Mo2Ti2C3Tx) possess ultrasmall particle sizes (∼2.1 nm) and increased dispersity of Pt NPs. As a result, the as-prepared Pt NPs/d-Mo2Ti2C3Tx 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-Mo2Ti2C3Tx is found to be 134 times higher. Meanwhile, it presents a high turnover frequency (8.49 H2 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.