Unravelling the adsorption and electroreduction performance of CO 2 and N 2 over defective and B, P, Si-doped C 3 Ns: a DFT study

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