Ultrafine PtCo Alloy Nanoclusters Confined in N-Doped Mesoporous Carbon Spheres for Efficient Ammonia Borane Hydrolysis

Developing cost-effective and high-efficiency catalysts for efficient ammonia borane (AB) hydrolysis is highly desirable but remains a great challenge. Ultrafine catalysts are attractive candidates in catalysis owing to abundant surface atoms. Herein, a series of ultrafine PtxCo1-x alloy nanoclusters with an average size of 1.6 nm are homogeneously anchored within the mesoporous channels of N-doped mesoporous carbon spheres (N-MCSs) through an enhanced strong electrostatic adsorption (SEA) strategy. The ultrafine PtCo nanoclusters confined in N-MCSs lead to superior catalytic performance toward the AB hydrolysis reaction. Particularly, the optimal Pt0.33Co0.67/N-MCSs catalyst exhibits excellent performance toward the AB hydrolysis reaction. The results reveal that the highest specific rate achieves 4902 mol(H2) mol(Pt)(-1) min(-1), which is approximately 18 times higher than that of the monometallic Pt/N-MCSs catalyst. Mechanistic studies adopting kinetic isotope effects demonstrate that the O-H cleavage of H2O molecules is the rate-determine step in the AB hydrolysis reaction. Inspired by the above results, a possible reaction mechanism is proposed, which will give a new viewpoint for the rational design of cost-effective catalysts for AB hydrolysis.

Automated summary

This study successfully developed a series of ultrafine PtxCo1-x alloy nanoclusters anchored in N-doped mesoporous carbon spheres (N-MCSs) using an enhanced strong electrostatic adsorption (SEA) strategy, showing superior catalytic performance for efficient ammonia borane (AB) hydrolysis. The optimal catalyst Pt0.33Co0.67/N-MCSs exhibited excellent performance with a high specific rate. Mechanistic studies revealed that O-H cleavage of H2O molecules is the rate-determine step in the AB hydrolysis reaction, providing insights for the rational design of cost-effective catalysts.