Enhanced Electrocatalysis for Energy-Efficient Hydrogen Production over CoP Catalyst with Nonelectroactive Zn as a Promoter

As a non-toxic species, Zn fulfills a multitude of biological roles, but its promoting effect on electrocatalysis has been rarely explored. Herein, the theoretic predications and experimental investigations that non-electroactive Zn behaves as an effective promoter for CoP-catalyzed hydrogen evolution reaction (HER) in both acidic and alkaline media is reported. Density function theory calculations reveal that Zn doing leads to more thermal-neutral hydrogen adsorption free energy and thus enhanced HER activity for CoP catalyst. Electrochemical tests show that a Zn0.08Co0.92P nanowall array on titanium mesh (Zn0.08Co0.92P/TM) needs overpotentials of only 39 and 67 mV to drive a geometrical catalytic current of 10 mA cm(-2) in 0.5 m H2SO4 and 1.0 m KOH, respectively. This Zn0.08Co0.92P/TM is also superior in activity over CoP/TM for urea oxidation reaction (UOR), driving 115 mA cm(-2) at 0.6 V in 1.0 m KOH with 0.5 m urea. The high HER and UOR activity of this bifunctional electrode enables a Zn0.08Co0.92P/TM-based two-electrode electrolyzer for energy-saving hydrogen production, offering 10 mA cm(-2) at a low voltage of 1.38 V with strong long-term electrochemical stability.