Ni and Fe nanoparticles, alloy and Ni/Fe-N coordination co-boost the catalytic activity of the carbon-based catalyst for triiodide reduction and hydrogen evolution reaction.

The design of high-performance early transition metal decorated carbon-based multiple active-site catalysts is of high significance for improving the efficiency of energy utilization. Highly dispersed FeNi alloy, Ni and Fe metal nanoparticles and 1D carbon nanotubes (CNTs) decorated metal-nitrogen species (Me-N) anchored carbon-based catalysts (Ni NP|Ni-NDC, Fe NP|Fe-NDC, FeNi|Ni/Fe-NDC) are prepared by a facile in-situ chemical synthesis. As-prepared three nanohybrid catalysts exhibit exceptional catalytic ability and stability for the alkaline hydrogen evolution reaction (HER) and triiodide reduction reaction (IRR). The power conversion efficiency of the dye-sensitized solar cell with the FeNi|Ni/Fe-NDC counter electrode catalyst reaches 8.58%. The overpotential and corresponding Tafel slope of electrocatalytic water splitting with FeNi|Ni/Fe-NDC catalyst exhibit 129 mV and 68 mV dec at the current density of 10 mA cm in alkaline solution, respectively. The enhanced catalytic performance of the as-designed hybrid catalysts can be attributed to the synergistic coupling effect of various components (the dispersed FeNi alloy, Ni and Fe metal nanoparticles, Ni/Fe-N active sites and 1D CNTs) of the hybrid catalyst.