Construction of Ni-based N-doped mesoporous carbon sphere for efficiently catalytic dichromate reduction with HCOOH at room temperature

•Ni NPs@N-doped carbon spheres are prepared by pyrolyzing precursors with Ni salts and utilized as a catalyst for reducing Cr(VI).•Ni-N-C600 can completely reduce the high concentrations of Cr(VI) (100 mg/L, 100 ml) within 7 min.•Ni-N-C600 shows superior activity, selectivity, and stability for reducing Cr(VI).•The reduction mechanism includes active hydrogen and electronic donation of functional groups.