Amorphous Alloy Architectures in Pore Walls: Mesoporous Amorphous NiCoB Alloy Spheres with Controlled Compositions <i>via</i> a Chemical Reduction.

Kang, Yunqing; Jiang, Bo; Yang, Juanjuan; Wan, Zhe; Na, Jongbeom; Li, Qian; Li, Hexing; Henzie, Joel et al. · ACS Nano · 2020

basic_science · Level V

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Abstract

Amorphous bimetallic borides are an emerging class of catalytic nanomaterial that has demonstrated excellent catalytic performance due to its glass-like structure, abundant unsaturated active sites, and synergistic electronic effects. However, the creation of mesoporous Earth-abundant bimetallic metal borides with tunable metal proportion remains a challenge. Herein, we develop a sophisticated and controllable dual-reducing agent strategy to synthesize the mesoporous nickel-cobalt boron (NiCoB) amorphous alloy spheres (AASs) with adjustable compositions by using a soft template-directed assembly approach. The selective use of tetrabutylphosphonium bromide (Bu<sub>4</sub>PBr) is beneficial to generate well-defined mesopores because it both moderates the reduction rate by decreasing the reducibility of M<sup>2+</sup> species and prevents the generation of soap bubbles. Our meso-Ni<sub>10.0</sub>Co<sub>74.5</sub>B<sub>15.5</sub> AASs generate the highest catalytic performance for the hydrolytic dehydrogenation of ammonia borane (AB). Its high performance is attributed to the combination of optimal synergistic effects between Ni, Co, and B as well as the high surface area and the good mass transport efficiency due to the open mesopores. This work describes a systematic approach for the design and synthesis of mesoporous bimetallic borides as efficient catalysts.