Abstract
Graphdiyne (GDY), featured with unique sp2, sp-hybridized form and inherent inhomogeneous electron distribution, retains great expectation to be developed into highly efficient electrocatalysts for hydrogen evolution reaction (HER). However, the state-of-the-art GDY-based electrocatalysts still suffer from weak catalytic activity and sluggish reaction kinetics originating from the severe scarcity of in-plane active sites and insufficient electrical conductivity. Targeted at this bottleneck issue, electronic structure regulation, recognized as an extremely precise technical route, is promising to improve HER performances of carbon-based electrocatalysts. Herein, a facile controllable chemical etching strategy is well leveraged to introduce sp2-hybridized carbon-oxygen bonds (Csp2-O) into GDY for precise manipulation both of its electronic and spatial structures. Experimental results and theoretical calculations coherently manifest that Csp2-O introduction into GDY can not only induce its electronic structure upheaval to strengthen surface electron transport capability, but also trigger intensive carbon-oxygen p-p orbital hybridization to enhance the catalytic activity of acetylenic bond sites. As a result, the optimal GDY sample after etching delivers excellent HER performance with an overpotential of only 101 mV at a current density of 10 mA cm-2 and a low Tafel slope of 54 mV dec-1, which surpasses most of reported metal-free based electrocatalysts. This work provides a universal route for precise modulation of inherent electronic structure in GDY, and can be further extended to boost the overall performances of other carbon-based catalysts
Surface defects and their impact on the electronic structure of Mo-doped CaO films: an STM and DFT study