Effect of carbon materials on In2S3 for PEC water splitting

Energy consumption is one of the primary global challenges in the present scenario. Photo electrochemical (PEC) water splitting is one of the attractive solutions to solve the energy crisis. The primary focus of this thesis work is to look at different carbon materials like reduced graphene oxide (RGO), carbon nanotubes (CNT), graphene for their role as photosensitizers of semiconductor materials in PEC water splitting. In this work, we have used β-In2S3 as a photoactive semiconductor which intrinsically has low electrical conductivity and high recombination rate. We have studied the property enhancement of β-In2S3 using various carbons. Pure In2S3 sample showed a photocurrent density of 0.25 μA/cm2. However, addition of carbons to β-In2S3 led to much improved photocurrents. Photocurrent densities of 0.007, 0.8 and 0.9 mA/cm2 are observed for In2S3 - Graphene (5 mg), In2S3 - CNT (2 mg), In2S¬3 - RGO (10 mg) composites respectively at 1.23 V vs RHE. The massive improvement in current densities in the case of RGO and CNT is due to the polar functional groups on their surface which helps in growth of In2S3 on the surface of these carbons. If we compare CNT vs RGO, we required much lower loading of CNT (2mg) to achieve the same current density as for RGO loading which required much higher loading (10mg). However, these studies showed that the use of carbons can significantly improve the performance of semiconducting materials for water splitting.