A confinement strategy for stabilizing two-dimensional carbon / CoP hybrids with enhanced hydrogen evolution

Highlights: : • Polydopamine (PDA) was employed to stabilize two dimensional Co-doped zeolitic imidazolate framework nanoleaf (Co-ZIF-L). • The PDA shell could carbonize to form a rigid carbon shell and have confinement effect on the Co-ZIF-L core. • The resultant CoP-NC inherit the merit of metal organic framework-derived carbon material and two-dimensional structure. • The electrocatalyst CoP-NC exhibits enhanced performance in hydrogen evolution reaction over wide pH range. -- Abstract: : Two-dimensional carbon/CoP hybrids catalysts usually exhibit extraordinary performance especially in hydrogen evolution reaction (HER) application because of their unique morphology which bring unique physical and chemical properties. Although Co-doped zeolitic imidazolate framework nanoleaf (Co-ZIF-L) is quite attractive as carbon-based catalyst precursor, carbonization and phosphorization processes would normally induce Co-ZIF-L derived CoP/N-doped carbon (CoP-NC) catalyst to occur structural collapse due to the shrinkage stress and strong reducibility of PH₃, seriously restricting the structural advantage of these catalysts. To this end, a carbon-shell confinement strategy by polydopamine (PDA) is developed to improve the structural stability of these catalysts. The precursor that Co-ZIF-L coated with PDA (Co-ZIF-L@PDA) has a more stable structure, which makes the electrocatalyst CoP-NC possess componential advantage and the merits of two-dimensional structure. The resultant CoP-NC exhibits enhanced activity and good stability for pH-universal HER. The overpotentials of CoP-NC at the current density of 10 mA cm⁻² are 145 mV in 0.5 M H₂SO₄ solution and 167 mV in 1 M KOH solution. Additionally, the electrocatalyst CoP-NC displays comparable activity and stability for HER in neutral media as well.