Three-dimensional monolayer graphene and TiO₂ hybrid architectures for high-efficiency electrochemical photovoltaic cells

Three-dimensional (3D), tubular-structured monolayer graphene networks were hybridized with TiO₂ nanoparticular layer for futuristic and robust electrode applications. A continuous form of 3D graphene with good carrier mobility provides a direct pathway for electrons to the current collector for a photoanode in dye-sensitized solar cells. This characteristic feature, coupled with its energy level, ensures an enhanced charge collection efficiency. Particular attention was paid to the graphene surface functionalization and the effective loading of TiO₂ nanoparticles to improve the light harvesting and minimize electron recombination for a photoanode. The optimal hybrid structure resulted in a 10% enhanced energy conversion efficiency, compared to the TiO₂-based analogue without graphene. The impedance spectra confirmed that the increase in photovoltaic performance was mainly driven by the efficient charge collection through the 3D, tubular-structured monolayer graphene. This new electrode prototype can serve as a good complement to conventional TiO₂ nanostructures.