Decorating CoNi layered double hydroxides nanosheet arrays with fullerene quantum dot anchored on Ni foam for efficient electrocatalytic water splitting and urea electrolysis

The design and construction of noble-metal-free electrocatalysts with superior activity, high efficiency and robust stability is still a big challenge for overall water and urea splitting. Herein, a novel hybrid electrocatalyst comprising fullerene quantum dot (FQD)-decorated CoNi layered double hydroxides (CoNi-LDH) nanosheet arrays anchored on porous Ni foam (NF) is elaborately fabricated. Beneficial from the synergetic effect between FQD and CoNi-LDH, the obtained FQD/CoNi-LDH/NF exhibits superior electrocatalytic activity for hydrogen and oxygen evolution as well as urea oxidation under ambient atmosphere. Impressively, to drive a current density of 10 mA cm−2, it requires cell voltages of only 1.59 and 1.45 V for overall water and urea electrolysis, respectively, in a two-electrode electrolyzer consisting of FQD/CoNi-LDH/NF as both anode and cathode. Furthermore, this catalyst also displays outstanding reaction kinetics and favorable catalytic stability. Both experimental and density functional theory (DFT) calculation results demonstrate that the charge transfer from FQD to CoNi-LDH could account for the excellent catalytic performance of the newly-synthesized catalyst, and the decorated FQD finely modulates the electronic structure of CoNi-LDH, favoring the adsorption of active hydrogen atom, and thus promote the catalytic process. The present work would provide useful guidance for designing and developing multifunctional and efficient electrocatalysts for hydrogen production.