Abstract
Hydrogen evolution reaction (HER) via the electrocatalytic reduction of water on metal-free catalysts may become a promising method for a sustainable energy supply in the future. However, compared with noble metals or transition metals, the carbon-based metal-free electrocatalysts show poor activity. Here, a novel coplanar metal-free catalyst (C2N-C3N) was designed for the first time to achieve better efficiency for electron transfer and water reduction. Through the DFT calculations, we discovered that the unique coplanar C2N-C3N structure can promote the directional transfer of electrons from C3N to C2N under the drive of built-in electric potential in the π-conjugated plane. To achieve higher performance in HER, the single atom doping by the substitution of boron is carried out. Remarkably, after the boron is doped, the barrier in the Tafel step decreases from 2.35 eV to 0.86 eV. Our results indicate that the novel B-doped coplanar C2N-C3N structure is a promising metal-free catalyst for HER.
Highlights
In traditional electrocatalytic hydrogen production, noble metals are often used as catalysts, such as platinum and gold[3]
In order to illustrate the stability of the novel structure, the molecular dynamics calculations were performed for C2N-C3N coplanar structure
In order to confirm our guess and improve the catalytic performance of Tafel mechanism in Hydrogen evolution reaction (HER) on the coplanar C2N-C3N, the C2 atom was doped by boron atom as the active sites for H2 evolution
Summary
In traditional electrocatalytic hydrogen production, noble metals are often used as catalysts, such as platinum and gold[3]. The study of metal-free catalysts for hydrogen evolution has become a hot topic, and the two-dimensional carbon based materials show remarkable performance in the field of catalysis. Compared with metal-containing materials, they have several advantages[7]: (1) to be synthesized; (2) active under visible light illumination They usually have a low activity for catalytic performance. As a classical modification approach, element doping promotes the charge transfer and the separation of electron-holes, but it generates new centers for carrier recombination[20,21]. Due to the weak interlayer van der Waals force, the generated carriers may still recombine in the interlayer space region[25] To overcome this issue, inducing a built-in electric field by in-plane heterostructure with different work function has become a significant approach[26]. The new structure could quickly trap photoexcited electrons and drive them to suitable active sites, which dramatically enhances the photocarrier separation and catalytic efficiency for HER29
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