NP monolayer supported transition-metal single atoms for electrochemical water splitting: a theoretical study.

The development of cost-effective and highly efficient electrocatalysts for water splitting is highly desirable but remains an ongoing challenge. Numerous single-atom catalysts (SACs) have achieved satisfactory performances in this area; however, non-carbon metal-free substrates have been rarely explored. Herein, we report a series of single-metal atoms supported on a novel two-dimensional NP monolayer as promising electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) by theoretical calculations. Our results disclose that Ti@NP, V@NP and Ir@NP exhibit desirable catalytic activity for the HER with extremely low of -0.004, -0.051, and 0.017 eV, respectively. More importantly, the calculated activation barriers for the Tafel reactions of these SACs are much lower than those for the benchmark Pt catalysts. In addition, Pt@NP shows the lowest of 0.495 V, followed by Rh@NP ( = 0.548 V), which are even superior to that of state-of-the-art IrO. This work highlights the potential application of metal-free upports in SACs, which also further enriches the application of a NP monolayer in other related electrochemical processes.