Enhanced catalytic reduction of Cr(VI) with formic acid over spherical bimetallic Ni-Co nanoalloy catalysts at room temperature

Exploring high-efficiency and low-cost catalysts for reducing Cr(VI) is one of the key problems in solving Cr(VI)-containing wastewater. In this paper, bimetallic Ni- and Co-based carbon sphere (Ni x Co y @NCS) was prepared by a simple hydrothermal-pyrolysis route, in which Ni-Co nanoalloys were uniformly dispersed on N -doped carbon sphere with average nanoparticles of 37.5 nm. The catalytic reduction performance of the hybrid catalyst Ni x Co y @NCS for Cr(VI) can be optimized by manipulation stoichiometry, and the catalytic ability of the Ni 1 Co 1 @NCS was much higher than that of other samples. This is because the synergy between Co and Ni NPs promotes the dehydrogenation efficiency of formic acid and the N doping improves the electron transport efficiency of the catalyst, and the strong protection of N -doped carbon for NPs ensured its excellent recycling ability and durability. In the existence of coexisting ions, the catalytic efficiency of the Ni 1 Co 1 @NCS is not affected at all. The reduction mechanism is mainly because of the active hydrogen during the dehydrogenation pathway of formic acid. This paper demonstrates that bimetallic Ni-Co-based materials have higher catalytic capacity than monometallic Ni or co-based materials.