Yuyang Cao,Shilong Yang,Yuting Liu,Xingyu Liu,Yue Li,Xiucheng Zheng,Zhikun Peng,Pu Liu
At present, controllable producing hydrogen from the catalytic hydrolysis of ammonia borane (AB, NH 3 BH 3 ) 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 Ru 0.50 Pd 0.50 @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 Ru 0.50 Pd 0.50 @WSC can be realized with the Zn 2+ /EDTA 2- system. This study provides an attractive metal alloy catalyst and some insights for the controllable hydrolysis of AB.
A monolithic complexed catalyst composed of a piece of Co foam decorated with Ru nanosheets has been fabricated. This catalyst has demonstrated excellent performance in catalyzing NaBH 4 hydrolysis under alkaline conditions. Most importantly, the bulky size of the developed catalyst provides convenience to control the start and stop of hydrogen production by manipulating the attachment and detachment between the catalyst and NaBH 4 solution. These features endow this catalyst with great potential for on-site hydrogen supply. Graphic Abstract
Weifeng Chen,Guo Lv,Jinrun Fu,Haiyan Ren,Jialu Shen,Jie Cao,Xiang Liu
Achieving the controlled release of H2 through an effective approach still faces many challenges. Herein, high-quality graphene quantum dots (GQDs) are synthesized from a new precursor, 1,2,4-trihydroxy benzene, and a multifunctional platform of Rh@GQDs is further developed for the controlled H2 evolution upon the hydrolysis of NH3BH3 (AB). More importantly, the designing concepts of multistep and stepless speed controls have been introduced in the domains of both H2 evolution for the first time. Through a novel designing protocol, the rate of H2 evolution can be freely regulated and constantly varied on demand by means of chelation between Zn2+ and ethylene diamine tetraacetic acid (EDTA). The density functional theory calculation indicates that Zn2+ has the priority to be adsorbed onto Rh(100) due to its larger adsorption energy (107.98 kcal·mol–1) than that of AB (36.36 kcal·mol–1). A controlling mechanism is presented such that Zn2+ will cover the active sites of the nanocatalyst to prevent the H2 evolution, and EDTA can chelate Zn2+ to reactivate the nanocatalyst for the production of H2, greatly facilitating use of this strategy in other catalytic reactions. Moreover, it is demonstrated that the protocol is equally valid for diverse hydrogen storage materials. Therefore, this work not only establishes whole new concepts for the controlled production of H2 but also explains their mechanism, thus remarkably advancing the utilization of H2 energy and significantly enlightening the controlled process of catalysis.
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