Amorphous/crystalline interface‐triggered electron redistribution on Rh(OH) ₃ /NiMoO ₄ for high‐efficient overall water and urea electrolysis at industrial current densities

Abstract Exploring earth‐abundant, highly effective, and stable electrocatalysts for overall water and urea electrolysis is urgent and essential for developing hydrogen energy technology. Herein, a simple interface engineering is used to fabricate an amorphous/crystalline Rh(OH) 3 /NiMoO 4 electrocatalyst. It exhibits an impressive trifunctional catalyst, with low overpotentials of 414 and 150 mV at 500 mA cm −2 for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), and with a low voltage of 1.457 V for urea oxidation reaction (UOR) at 500 mA cm −2 . The outstanding OER, HER, and UOR activities are attributed to the unique amorphous/crystalline heterostructure of Rh(OH) 3 /NiMoO 4 , which possesses special hydrophilic features that accelerate mass transfer and provide abundant exposed active sites and appropriate defects. In situ Raman spectra reveal that the incorporation of amorphous Rh(OH) 3 facilitates the catalyst reconstruction. The two‐electrode electrolyzer needs cell voltages of only 1.93 and 1.59 V to achieve a current density of 500 mA cm −2 and remarkable durability for more than 50 h at 500 mA cm −2 for overall water and urea‐assisted splitting. This work provides a new idea for using amorphous/crystalline heterostructure to design electrocatalysts for overall water and urea electrolysis at industrial current densities.