Enhanced catalytic performance of MoO3/MoS2-rGO counter electrode towards a Pt-free dye sensitized solar cell

The redox process at the electrolyte/counter electrode (CE) interface is a crucial step in achieving efficient charge flow cycles in DSSCs. The work focuses on enhancing the charge kinetics between the electrolyte, and MoO3 CE using MoS2-reduced graphene oxide (rGO) composites. Different weight percentages of rGO (5 wt%, 10 wt%, and 15 wt%) are composited with MoS2. The MoO3 surface is modified by screen-printing MoS2, and MoS2-rGO on it. The dense network of MoS2, and rGO at the optimized concentration furnishes Pt-like electrocatalytic activity to MoO3. The 10 wt% of rGO in MoS2 (M/MSG10) imparts favourable properties to MoO3 CE by lowering the charge transfer resistance by 2.6-fold and enhancing the electrocatalytic performance. The limiting, and exchange current densities increase by 2.2, and 2.9 times, respectively, compared to MoO3. M/MSG10 CE exhibits a maximum power conversion efficiency of 5.0 %, which is 2.9 times higher than MoO3. This champion device outperforms the conventional Pt CE by recording an efficiency 1.1-fold higher. This study identifies Pt-free CE, specifically MoO3/MoS2-rGO, as a potential candidate to reduce the cost of DSSCs, and promote commercialization.