Enhanced hydrogen evolution reaction activity of nitrogen deficient $hg-C_{3}N_{4}$ quantum dot

TL;DR

This study uses first-principles calculations to show that nitrogen-deficient $hg-C_{3}N_{4}$ quantum dots are promising electrocatalysts for hydrogen evolution, especially when dissolved in ethanol, due to their favorable electronic and catalytic properties.

Contribution

It introduces nitrogen vacancies in $hg-C_{3}N_{4}$ quantum dots and demonstrates their enhanced HER activity through computational analysis, highlighting their potential in sustainable hydrogen production.

Findings

Nitrogen vacancies improve HER catalytic performance.

Dissolving quantum dots in ethanol drastically reduces overpotential.

Quantum dots show stability and favorable electronic properties for HER.

Abstract

The present study investigates the catalytic performance of a $hg-C_{3}N_{4}$ quantum dot aimed at enhancing electrochemical water splitting, using the first-principles density functional theory. The size of the considered quantum dot lies within the range reported experimentally (2nm - 4nm) [Zhou et al. ACS Nano 9, 12480 (2015)]. The nitrogen vacancies are created in the considered $hg-C_{3}N_{4}$ structure to simulate the realistic scenario, as the presence of nitrogen and carbon defects are reported in the synthesized $hg-C_{3}N_{4}$ quantum dots. First, the structural and vibrational properties are computed to ensure the stability of the nitrogen deficient $hg-C_{3}N_{4}$ quantum dots, and subsequently, their electronic and hydrogen evolution reaction (HER) properties are investigated. The calculate HER parameters, i.e., adsorption energies, Gibbs free energies, and overpotentials demonstrate that the considered $hg-C_{3}N_{4}$ quantum dot with nitrogen vacancies can be used as a moderately effective electrocatalyst for HER performance. We also considered the quantum dot to be dissolved in water and ethanol, and find that the overpotential gets drastically reduced to 16 mV for the alcohol dissolved quantum dot, while some significant reduction is seen for the aqueous solution also. As a result, this study suggests that the nitrogen-deficient $hg-C_{3}N_{4}$ quantum dots dissolved in ethanol are excellent candidates for catalysis aimed at sustainable hydrogen production via electrochemical water splitting.