Engineering defect-rich aluminum-doped cobalt phosphide nanosheet as a high-performance electrocatalyst for acidic hydrogen evolution

The development of low-cost, high-activity electrocatalysts for the hydrogen evolution reaction (HER) has garnered considerable research interest in recent years. Herein, we develop a defect-rich, Al-doped Co-P (Co-Al-LDH-a-p) nanosheet catalyst via NaOH activation, which exhibits high efficiency and robust stability as an HER electrocatalyst. The morphology and structure of Al-Co precursor remain almost unchanged after NaOH activation, but the derived Co-Al-LDH-a-p phosphide shows the poor crystallinity, suggesting the loss of long-range ordered structure and the formation of structural defects after NaOH activation. When utilized as an electrocatalytic cathode in 0.5 M H₂SO₄ solution, Co-Al-LDH-a-p catalyst shows a superior hydrogen-evolution performance with a current density of 10 mA cm^-2 at a low applied overpotential (η₁₀) of only 86 mV, a high faradaic efficiency of close to 100% and an excellent durability with no degradation for η₁₀ after 2,000 cycles. Therefore, NaOH activation is a feasible method to synthesize defect-rich HER catalysts by selectively etching Al without any organic component.