Unravelling the adsorption and electroreduction performance of CO and N over defective and B, P, Si-doped CNs: a DFT study.

Two-dimensional carbon-based materials have great potential for electrocatalysis. Herein, we screen 12 defective and doped CN nanosheets by evaluating their CORR and NRR activity and selectivity the HER based on density functional theory calculations. The calculation results suggest that all 12 CNs can enhance CO adsorption and activation. And P-V-CN is the best electrocatalyst for the CORR towards HCOOH with = -0.17 V, which is much more positive than most of the reported values. B-CN and P-CN are also good electrocatalysts that promote the CORR towards HCOOH ( = -0.38 V and -0.46 V). Moreover, we find that Si-CN can reduce CO to CHOH, adding an alternative option to the limited catalysts available for the CORR to CHOH. Furthermore, B-V-CN, B-V-CN, and Si-V-CN are promising electrocatalysts for the HER with |Δ| ≤ 0.30 eV. However, only three CNs of B-V-CN, Si-V-CN, and Si-V-CN can slightly improve N adsorption. And none of the 12 CNs are found to be suitable for the electrocatalytic NRR because all the Δ values are larger than the corresponding Δ values. The high performance of CNs in the CORR stems from the altered structure and electronic properties, which result from the introduction of vacancies and doping elements into CN. This work identifies suitable defective and doped CNs for excellent performance in the electrocatalytic CORR, which will inspire relevant experimental studies to further explore CNs for electrocatalysis.