Controlled synthesis of CrxPy-a/ComPn-b nanoarray on nickel foam as efficient electrocatalyst for overall urea splitting

Developing highly efficient bifunctional urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) catalysts for urea splitting to hydrogen are one of the strategies to cope with the energy crisis. Here, a series of Cr_xP_y-a/Co_mP_n-b composites were synthesized on Ni foam through hydrothermal and low-temperature phosphorization process for the first time. It is worth noting that Cr_xP_y-1/Co_mP_n-3@NF exhibited excellent UOR performance (1.331 V at 100 mA cm^?2) and HER performance (0.299 V at 100 mA cm^?2) in an electrolyte of 1 M KOH and 0.5 M urea due to the synergistic effect of Cr–Co. The Cr_xP_y-1/Co_mP_n-3@NF||Cr_xP_y-1/Co_mP_n-3@NF two-electrode system call for only 1.52 V to provide current density of 10 mA cm^?2, which is one of the best electrochemistry performances reported up to now. Experimental analysis show that the promoted electrochemistry performances is assigned to faster charge transfer rate, the exposure of more reaction site and better properties of metals. Density Functional theory (DFT) results demonstrate that the presence of the Co_mP_n material accelerates the kinetics of hydrogen production and the Cr_xP_y material improves the properties of metals for the electrode. The work provides a new idea to develop the environmentally friendly and low cost overall urea splitting catalyst with transition metals instead of noble metals.