Supramolecular Nanosheet evolution into BC3N matrix improves the hydrogen evolution reaction activity in the pH universality of highly dispersed Pt nanoparticles

Abstract

Electrochemical hydrogen evolution reaction (HER) is a green and convenient way to produce hydrogen with high calorific value and zero environmental pollution, but the precious metal Pt, which catalyzes its efficient operation, faces the dilemma of resource scarcity. Before finding an HER catalyst to replace platinum-based materials, morphology control engineering can achieve high-efficiency hydrogen production with a lower platinum input. Here, we used a supramolecular assembly (host: cucurbituril[7]; guest: closo-[B₁₂H₁₂]²⁻) with weak reducibility as a carrier to convert Pt⁴⁺ into ultrafine and highly dispersed Pt nanoparticles (BOPs@Pt) in situ, and the supported Pt-based catalyst (BC₃N@Pt) obtained after pyrolysis had the ability to very efficiently catalyze HER. BC₃N@Pt exhibited excellent performance in catalyzing HER in the full pH range. Among them, the overpotentials to achieve a current density of 10 mA cm⁻² in the media of pH = 14, pH = 7 and pH = 1 were only 26.1 mV, 38.5 mV and 23.1 mV, respectively, and the corresponding Tafel slopes were as low as 41.59 mV dec⁻¹, 59.05 mV dec⁻¹, and 61.07 mV dec⁻¹, respectively. In terms of mass activity, the rate of HER driven by BC₃N@Pt was at least three times than that achieved with the commercial 20 wt% Pt/C. The density functional theory (DFT) calculations verified that B doped on CN changes the local electronic distribution, facilitates water dissociation and hydrogen adsorption, and hence enhances the HER activity. The annealing treatment converts the organic polymer into an inorganic BC₃N matrix, which not only accelerates the electron transfer rate in HER, but also ensures the stability of BCN@Pt when catalyzing HER in the entire pH range.