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 (NixCoy@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 Nix-Coy@NCS for Cr(VI) can be optimized by manipulation stoichiometry, and the catalytic ability of the Ni1C-o1@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 effi-ciency 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 Ni1Co1@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.

Automated summary

In this study, bimetallic Ni and Co-based carbon sphere catalysts were prepared and showed excellent catalytic reduction performance in lowering Cr(VI) in wastewater. The Ni1C-o1@NCS catalyst exhibited higher catalytic capacity compared to other samples, which can be attributed to the synergy between Co and Ni nanoparticles and the protection provided by N-doped carbon spheres. Furthermore, the catalytic efficiency of the Ni1Co1@NCS catalyst was unaffected in the presence of coexisting ions.