Multimetal-based nitrogen doped carbon nanotubes bifunctional electrocatalysts for triiodide reduction and water-splitting synthesized from polyoxometalate- intercalated layered double hydroxide pyrolysis strategy

Abstract Over the years, transition metal-based hybrids have been advocated as one of the most promising classes of non-noble catalysts and investigated exclusively for the electrocatalytic triiodide reduction reaction (IRR) or hydrogen evolution reaction (HER). However, there is lack of effective strategy to address their site accessibility, intrinsic activity and structural stability issues, and their successful utilization as bifunctional catalysts of IRR and HER is rarely explored. Herein, presented is a multimetal-based carbon nanotube hybrid (CoFeNiMo@NCNT), synthesized from a novel polyoxometalate (POM)-intercalated layered double hydroxide (LDH) pyrolysis strategy, as an efficient catalyst for IRR and HER. During both electrochemical IRR and HER, the regulated NCNT provides a highway for electron migration and acts as a network for I3−/H+ adsorption. Benefitting from the features of porous structure, multimetal component and fast electron transfer, the CoFeNiMo@NCNT catalyst delivers a high power conversion efficiency of 6.46 % when assembled as counter electrode in dye-sensitized solar cell, superior to Pt benchmark. Furthermore, it mediates efficient HER with a relatively small overpotential of 209.9 mV at 10 mA cm-2. The strategy to achieve tunable catalytic properties via in situ pyrolysis well-defined inorganic materials paves a new way to design cost-effective and efficient bifunctional catalysts.