Defect-rich hollow double-shell bimetallic phosphides for electrocatalytic hydrogen evolution over a wide pH range

Developing non-precious metal catalysts with high catalytic efficiency remains a challenge in the electrocatalytic hydrogen production field. Herein, a defect-rich double-shell CNHC-O-P microsphere is constructed by urea etching and then a step-by-step phosphating process via Co 3 Ni 7 -MOFs as the precursor. During the urea etching process, the organic ligands in MOFs are substituted by CO 3 2– and OH – anions to form basic carbonate double-shell microsphere. Then, the released CO 2 and H 2 O molecule during the calcination process produce a porous and defective oxide double-shell microsphere. Furthermore, more lattice distortions and defects are formed through O and P exchanging during the gas phosphating process. The unique defect-rich and double-shell structure provides a rich and accessible active site for enhanced HER performance. The optimized CNHC-O-P shows the overpotentials of 197 mV, 253 mV, and 245 mV at 10 mA·cm −2 current density in 1 M KOH, 0.5 M H 2 SO 4 , and 1 M PBS solution, separately. This work provides a new method for designing and synthesizing defect-rich and double-shell nanomaterials for energy storage and conversion application.