Hybridization of Mn/Ta bimetallic oxide and mesh-like porous bio-carbon for boosting copper reduction for D35/Y123-sensitized solar cells and hydrogen evolution

Developing high-performance and low-cost catalysts for replacing Pt-based catalysts is a significant challenge for solar cells and water splitting applications. In this work, a bifunctional hybrid catalyst of MnTa2O6@MPC (MPC: mesh-like bio-based porous carbon) was synthesized, using a co-precipitation approach. Benefiting from the high specific surface area (332.743 m2 g−1), integrating the merits of the electrical conductivity of MPC, the outstanding electrocatalytic ability of MnTa2O6, and the synergistic effect between MnTa2O6 and MPC, the catalytic activity of MnTa2O6@MPC was significantly enhanced. To boost the photovoltaic performance of dye-sensitized solar cells, a novel Cu2+/Cu+ redox mediator and dye (Y123, D35) were adopted for replacing the traditional I3-/I- redox mediator and N719 dye, respectively. The resulting advanced solar cell with the Cu2+/Cu+ redox mediator based on the MnTa2O6@MPC counter electrode catalyst exhibited a photovoltage of ~0.88 V, and cell efficiencies of 3.41% and 1.92% for the D35 and Y123 dye systems, respectively, which are respectively 16% and 8% higher than that of Pt. MnTa2O6@MPC also exhibited significant catalytic ability for hydrogen production, yielding a small overpotential of 141.9 mV at a current density of 10 mA cm−2 and a small Tafel slope of 105.0 mV dec−1 in an alkaline medium. This work provides promising guidance for designing bifunctional hybrid electrocatalysts for high-performance new energy devices.