Different types of Nitrogen-doped CQDs loaded by CoP used as OER electrocatalysts

Abstract

In recent years, CoP catalysts loaded with N-doped carbon dots (NCQDs) have gained attention as promising metal-free electrocatalysts due to their low cost, simple preparation process, and excellent electrocatalytic performance. However, few studies have investigated the effect of different types of nitrogen doping on the catalytic performance of NCQDs in electrocatalysis. In this study, NCQDs doped with graphite/amine N, pyridine N, and pyrrole/amine/pyridine N were prepared using various small molecule precursor systems, and control experiments were conducted with CQDs without nitrogen doping. Electrochemical tests demonstrated that nitrogen doping can enhance the electrocatalytic performance of the NCQDs. Notably, CoP modified with pyrrole/amine/pyridine N-doped CQDs (NCQDs-3) exhibited significantly improved electrocatalytic performance, the largest specific surface area, and the lowest charge transfer resistance. Pyridine N was found to increase structural defects, pyrrole N could supply electrons to create an electron-rich state in CoP, while amine and graphite N could reduce the bandgap. Furthermore, the Co-N-C covalent bonds between CoP and CQDs enhanced conductivity. Therefore, the electrochemical performance of the electrocatalyst was closely related to the synergy between the nitrogen atom doping mode.