Nitrogen doping excited Ru and Ti3C2−xNx support for hydrogen generation from ammonia borane

Abstract

The research and development of efficient catalysts is very important for the sustainable utilization of hydrogen energy. Herein, we designed the Ru/Ti3C2−xNx catalysts using N-doped two-dimensional material MXene (Ti3C2−xNx) as support toward hydrogen generation from ammonia borane (AB) hydrolysis. Due to the confinement and anchoring effects of Ti3C2−xNx, the as-prepared Ru/Ti3C2−xNx catalysts show an ultrafine particle size of 1.55 nm and remarkable AB hydrolysis activity with high turnover frequency (TOF) value of 1334 min−1 and rB value of 297 × 103 mL·min−1·gRu−1 at 298 K. XPS results show that the doped N atoms in Ti3C2−xNx support provide electron-feeding effect for Ru in the reaction to form electron-rich Ru. The isotope experiments confirm that the dissociation of H2O is the rate-determining step (RDS) in AB hydrolysis reaction catalyzed by Ru/Ti3C2−xNx. According to the density functional theory (DFT) calculations, the N atoms introduced into Ti3C2−xNx decrease the dissociation energy of O–H bond in H2O molecules, accelerating the desorption of H* from Ti3C2−xNx surface. This research provides a strategy to enhance synergistic interaction between support and metal through N-doping, so as to effectively improve the catalytic performance of heterogeneous catalysts.