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Platinum (Pt)-based alloys are considerably promising electrocatalysts for the reduction of I–/I3– and Co2+/Co3+ redox couples in dye-sensitized solar cells (DSSCs). However, it is still challenging to minimize the dosage of Pt to achieve comparable or even higher catalytic efficiency. Here, by taking full advantages of the Mott–Schottky (M–S) effect at the metal–semiconductor interface, we successfully strategize a low-Pt-based M–S catalyst with enhanced electrocatalytic performance and stability for the large-scale application of DSSCs. The optimized M–S electrocatalyst of Ni3S4–Pt2X1 (X = Fe, Ni) heteronanorods is constructed by rationally controlling the ratio of Pt to transition metal in the hybrids. It was found that the electrons transferred from Ni3S4 to Pt2X1 at their interface under the Mott–Schottky effect result in the concentration of electrons onto Pt2X1 domains, which subsequently accelerates the regeneration of both I–/I3– and Co2+/Co3+ redox shuttles in DSSCs. As a result, the DSSC with N...

Metal-semiconductor based Mott-Schottky (M-S) heterojunctions combining two or more functionalities in one unit can effectively improve their catalytic activity and durability due to the electronic coupling effects between distinct components. Although tremendous progress has been made in structure fabrication, controllable synthesis of one-dimensional (1D) M-S heterojunction and its application as electrocatalysts is still lacking. Herein, uniform and well-defined 1D Ni3S4-PtCo heteronanorods are synthesized via a facile solution method and employed as counter electrode (CE) catalyst in the dye-sensitized solar cells (DSSCs). By exploiting the benefits of both structural and compositional characteristics, namely, the direct electrical pathways of 1D nanostructure, optimized work function of metal alloy as well as the synergistic effect between Ni3S4 and PtCo, the as-designed Ni3S4-PtCo heteronanorods exhibit excellent catalytic activity and stability toward the reduction of triiodide in DSSCs. A DSSC with Ni3S4-PtCo achieves a high power conversion efficiency of 8.66% under AM1.5G illumination (100 mW cm−2), higher than that of pristine Pt-based device (8.12%). Moreover, the fast activity onset and relatively long stability further demonstrate that the Ni3S4-PtCo heteronanorod is a promising alternative to Pt in DSSCs. Considering the diversity of structures and components in heterostructures, the strategy presented here can be extended for synthesizing other well-defined 1D M-S heterojunctions, which may be used in the fields of catalysis, energy conversion and storage.

Aqueous polysulfide/iodide redox flow batteries are attractive for scalable energy storage due to their high energy density and low cost. However, their energy efficiency and power density are usually limited by poor electrochemical kinetics of the redox reactions of polysulfide/iodide ions on graphite electrodes, which has become the main obstacle for their practical applications. Here, CoS2/CoS heterojunction nanoparticles with uneven charge distribution, which are synthesized in situ on graphite felt by a one-step solvothermal process, can significantly boost electrocatalytic activities of I−/I3− and S2−/Sx2− redox reactions by improving absorptivity of charged ions and promoting charge transfer. The polysulfide/iodide flow battery with the graphene felt-CoS2/CoS heterojunction can deliver a high energy efficiency of 84.5% at a current density of 10 mA cm−2, a power density of 86.2 mW cm−2 and a stable energy efficiency retention of 96% after approximately 1000 h of continuous operation., Polysulfide/iodide redox flow batteries are promising due to low cost and high-solubility components, but are limited by energy efficiency and power density. Here the authors fabricate heterojunction electrocatalysts to achieve improved performance in a polysulfide/iodide redox flow battery.

Wurtz-stannite Cu2CdGeS4 nanocrystals were synthesized via a facile hot-injection method at a low temperature. They exhibited low charge transfer resistance at the electrolyte-electrode interface and high electrocatalytic activity for the reduction of I3(-) in dye-sensitized solar cells (DSSCs). Moreover, this DSSC showed a power conversion efficiency of 7.67%, comparable to the Pt-based device (7.54%).