Enhanced photoelectrochemical performance of P-doped g‑C3N4/Zn0.5Cd0.5S heterojunction photocathode for water splitting
Waseem Zeb, Amna Altaf, Muhammad Aamir, Nadeem Baig, Irshad Baig, Ayman Nafady, Muhammad Sharif, Sher Muhammad, Manzar Sohail
Abstract
Photoelectrochemical (PEC) hydrogen evolution reaction at semiconductor photocathode in the presence of visible light is a promising way to harvest renewable energy. Graphitic carbon nitride (g-C3N4) has intriguing properties, making it highly favorable for photoelectrode engineering. This work demonstrated P-doped g-C3N4 nanosheets (PCN-Nss) and Zn0.5Cd0.5S heterojunction (PCN-Nss/ZCS-40) for PEC hydrogen evolution reaction using simulated sunlight. A facile and simple two-step strategy developed PCN-Nss/ZCS-40 photocathode; including co-precipitation of ZnCdS in the highly dispersed suspension of PCN-Nss and then drop-casting it on the surface of a conductive substrate. The intimate contact between PCN-Nss and ZnCdS at the molecular level due to the formation of heterojunction efficiently triggers charge separation, suppressing electron-hole pair recombination and easing the movement of photo-generated holes towards the conductive substrate. PCN-Nss/ZCS-40 (40% P-C3N4 by weight) showed substantially improved photocurrent response (−12 µA cm−2) at −0.6 V vs Ag/AgCl reference electrode in 0.2 M Na2S solution, which is almost 40 times greater than simple P-C3N4 nanosheets under the same conditions. This work will expose new applications for P-doped graphitic carbon nitride-based heterostructures for PEC water splitting.