Controllably hydrolytic dehydrogenation of NH3BH3 over micropore-dominant porous carbon confined RuPd ultrafine alloys

Abstract

At present, controllable producing hydrogen from the catalytic hydrolysis of ammonia borane (AB, NH3BH3) is very meaningful and challenging. Therefore, developing an effective catalyst for the reaction, clarifying its catalytic mechanism, and realizing controllable hydrogen release are extremely indispensable. In this work, RuPd nanoalloys are evenly confined by the agricultural waste wheat straw-derived carbon (denoted as WSC) with a micropore-dominant porous structure and plentiful N/O doping. Attributing to the particular support effect of WSC and the interesting RuPd alloy effect, the as-prepared bimetallic catalysts provide encouraging catalytic performance in AB hydrolysis. Catalyzed by the optimal Ru0.50Pd0.50@WSC, the turnover frequency (TOF) and hydrogen evolution rate are 214.5 min−1 and 50800 mL min−1 g−1, respectively, and the apparent activation energy is only 23.2 kJ mol−1. Moreover, introducing proper NaOH (1.5 M) further accelerates hydrogen release (TOF = 502.8 min−1, specific rate = 119100 mL min−1 g−1). The isotope experiments depict a kinetic isotope effect of 2.85, evidencing the vital role of the hydrogen–oxygen bond scission in this catalytic reaction. More importantly, benefitting from the difference in adsorption energy and strong coordination ability, the “on–off” control for the hydrolysis of AB over Ru0.50Pd0.50@WSC can be realized with the Zn2+/EDTA2- system. This study provides an attractive metal alloy catalyst and some insights for the controllable hydrolysis of AB.