g-C3N4:Sn-doped In2O3 (ITO) nanocomposite for photoelectrochemical reduction of water using solar light.

Graphitic carbon nitride (g-C 3 N 4) nanosheets are well studied for photocatalytic water splitting using solar light. However, its photocatalytic activity is restrained due to fast recombination of photo-generated electron-hole pairs. Here, we introduce Sn-doped In 2 O 3 (ITO) nanocrystals (NCs) as co-catalysts with g-C 3 N 4 nanosheets, forming g-C 3 N 4 :ITO (2 ​wt%) nanocomposites, for photoelectrochemical (PEC) reduction of water to H 2. The co-catalyst has two major impacts: (i) enhances charge transfer from g-C 3 N 4 to ITO NCs suppressing the recombination of photoexcited electron-hole pair, and (ii) reduces charge transfer resistance at electrode/electrolyte interface. Both these aspects improve PEC activity of the nanocomposites. Our g-C 3 N 4 :ITO nanocomposites photoelectrode shows a photocurrent density of -70 ​μA/cm2 for reduction of water to H 2 , whereas the pristine g-C 3 N 4 nanosheet photoelectrode shows -12 ​μA/cm2 photocurrent density at 0.11 ​V versus reversible hydrogen electrode (RHE). This (~6 times) enhancement in photocurrent density by ITO NCs co-catalyst is reasonably high compared to other co-catalysts for g-C 3 N 4 reported in prior literature. This paper is on solar light driven photoelectrochemical (PEC) reduction of water to H 2. Sn-doped In 2 O 3 (ITO) nanocrystals is introduced as co-catalyst with graphitic carbon (g-C 3 N 4) nanosheets photocatalyst. The g-C 3 N 4 :ITO nanocomposites show ~6 times higher PEC activity compared to g-C 3 N 4 nanosheets. This enhancement is because of ITO nanocrystal co-catalyst facilitating the charge separation and charge transfer processes on the nanocomposite. Image 1 • Solar light driven photoelectrochemical (PEC) reduction of water to H 2. • ITO nanocrystals is introduced as co-catalyst with g-C 3 N 4 nanosheets photocatalyst. • g-C 3 N 4 :ITO nanocomposites show superior PEC activity compared to g-C 3 N 4 nanosheets. • ITO co-catalyst facilitates charge separation and charge transfer processes. [ABSTRACT FROM AUTHOR]