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A series of TiO 2 –graphene stacked photoanodes for dye-sensitized solar cells (DSSCs) were fabricated by electrospray (E-spray) deposition. Among devices incorporating single graphene layer with different deposition times, device with 1 min graphene deposition gave the best performance. For multi-graphene-layer involved devices, best result was obtained with 3 layers of graphene. The working principles were analyzed by scanning electron microscopy, transmittance spectra, electrochemical impedance spectroscopy and incident-photo-conversion efficiency data. We found that although graphene layers incorporated in TiO 2 photoanode slightly decreased dye adsorption, they were able to significantly improve the electron transport, and the charge recombination at the interfaces of TiO 2 /dye and TiO 2 /electrolyte were greatly suppressed, leading to dramatic improvement in power conversion efficiency. When inserting three layers of pure graphene into the TiO 2 photoanode, high efficiency of 8.9% was obtained, constituting an over 23.6% improvement. Further increasing graphene layers to five, although electron lifetimes is the longest, both the largest charge transfer resistance and the least amount of the dye loading lead to the lowest device efficiency. Our work demonstrated, that pure graphene layer can be successfully incorporated into TiO 2 photoanode by E-spray method with easiness of thickness control and the photoanode with graphene/TiO 2 alternatively layered structure is an excellent candidate for DSSCs. [ABSTRACT FROM AUTHOR]

Exploiting photocatalysts with characteristics of cost effectiveness, environmental friendliness, visible light response, high reactivity and good durability is a great challenge for solar H 2 generation. Here, we synthesis of MoS 2 -graphene composite as a highly-efficient cocatalyst to enhance the photocatalytic activity of ZnIn 2 S 4 under visible light irradiation. Through the optimizing of each composition proportion, the hierarchical MoS 2 -graphene/ZnIn 2 S 4 photocatalyst shows the highest H 2 evolution rate of 4169 μmol h −1 g −1 under visible light irradiation in presence of Na 2 S and Na 2 SO 3 as sacrificial reagents when the content of MoS 2 -graphene is 1.2 wt% and the weight ratio of MoS 2 to graphene is 10:1, which is almost 22.8 times higher than that of pure ZnIn 2 S 4 . More importantly, the ternary MoS 2 -graphene/ZnIn 2 S 4 composite exhibits much higher photocatalytic activity than Pt-loaded ZnIn 2 S 4 photocatalyst, suggesting that the MoS 2 -graphene composite can act as a more efficient cocatalyst than the commonly used Pt metal. The superior catalytic activity of MoS 2 -graphene cocatalyst can be assigned to the positive synergistic effect between MoS 2 and graphene, which act as a hydrogen evolution reaction catalyst and an electron transport bridge, respectively. The effective charge transfer from ZnIn 2 S 4 to MoS 2 through graphene is demonstrated by the significant enhancement of photocurrent responses in MoS 2 -graphene/ZnIn 2 S 4 composite photoelectrodes. [ABSTRACT FROM AUTHOR]