Improved photocatalytic activity and stability of InGaN quantum dots/C3N4 heterojunction photoelectrode for CO2 reduction and hydrogen production

Abstract

Photocatalytic conversion of CO2 to produce fuel is considered a promising approach to reduce CO2 emissions and tackle energy crisis. GaN-based materials have been studied for CO2 reduction because of their excellent optical properties and band structure. However, low photocatalytic activity and severe photocorrosion of GaN-based photoelectrode greatly limit their applications. In this work, photocatalytic activity was improved by adopting InGaN quantum dots (QDs) combined with C3N4 nano-sheets as photoanode, and thus the efficiency of CO2 reduction and the selectivity of hydrogen production were increased significantly. In addition, the photoelectron-chemical corrosion of photoelectrodes has been apparently controlled. InGaN QDs/C3N4 has the highest CO and H2 productions rates of 14.69 μmol mol−1 h−1 and 140 μmol mol−1 h−1 which were 2.2 times and 14.5 times than that of InGaN film photoelectrode, respectively. The enhancement of photocatalytic activity is attributed to C3N4 modification and a large electric dipole forming on the surface of InGaN QDs, which facilitate the separation and transfer of photo-generated carriers and thus promote CO2 reduction reaction. This work provides a promising strategy for the development of GaN-based photoanodes with superior stability and efficiency.