Atomic-thin VN layer@N-doped carbon as efficient oxygen reduction reaction electrocatalysts

The defect engineering is of vital importance for electrocatalysts because it can provide an additional yet advanced tier to further boost catalysis, especially for ultrathin nanosheets of transitional metal compounds with a high surface to bulk ratio and more importantly the ability to engineer the defect along the longitudinal direction of the grain boundaries. Herein, we developed super-thin and ordered face-centered cubic VN nanosheets with grain boundaries using a new facile and in-situ method. The structural and morphological properties of the prepared samples were investigated, finding that the temperature has significant effects on the distribution of sheets. The thickness of nanosheets is only 1.3 nm the same as that of three cubic VN crystal unit cells, which is pivotal to the electrochemical reaction. The detailed electrocatalysts results show that the VN nanosheets (NSs) exhibit interesting ORR performance with the onset potential of 0.93 V and a half-wave potential of 0.86 V. The evenly distributed VN NSs display the highest durability with only 5% attenuation after 50000s operation for the oxygen reduction reaction. We provide a new strategy to synthesize super-thin nitrides nanosheet structure, highlighting the strong correlation between surface engineering and the performance of electrocatalysts for potential practical oxygen reactions.

Automated summary

Defect engineering is crucial for electrocatalysts, especially for ultrathin nanosheets of transitional metal compounds with high surface to bulk ratio that can be engineered along the grain boundaries. In this study, we developed super-thin and ordered face-centered cubic VN nanosheets with grain boundaries using a facile and in-situ method. The prepared samples showed significant temperature-dependent sheet distribution, and the thickness of the nanosheets was found to be crucial for electrochemical reactions. The VN nanosheets demonstrated interesting oxygen reduction reaction performance with high onset potential and durability, highlighting the importance of surface engineering in electrocatalyst performance for potential practical applications.