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MoS2 has attracted attention as a promising hydrogen evolution reaction (HER) catalyst and a supercapacitor electrode material. However, its catalytic activity and capacitive performance are still hindered by its aggregation and poor intrinsic conductivity. Here, hollow rGO sphere-supported ultrathin MoS2 nanosheet arrays (h-rGO@MoS2) are constructed via a dual-template approach and employed as bifunctional HER catalyst and supercapacitor electrode material. Because of the expanded interlayer spacing in MoS2 nanosheets and more exposed electroactive S-Mo-S edges, the constructed h-rGO@MoS2 architectures exhibit enhanced HER performance. Furthermore, benefiting from the synergistic effect of the improved conductivity and boosted specific surface areas (144.9 m2 g−1, ca. 4.6-times that of pristine MoS2), the h-rGO@MoS2 architecture shows a high specific capacitance (238 F g−1 at a current density of 0.5 A g−1), excellent rate capacitance, and remarkable cycle stability. Our synthesis method may be extended to construct other vertically aligned hollow architectures, which may serve both as efficient HER catalysts and supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Ceramic TiB 2 , a layered metal diboride with remarkable conductivity and chemical stability, are potential electrocatalyst towards hydrogen evolution reaction (HER). However, high overpotential (>1 V) is required for pristine TiB 2 to drive water splitting, which is less than satisfactory in future hydrogen economy. Herein, conductive polypyrrole (PPy) encapsulating TiB 2 (TiB 2 @PPy) has been developed via vapor phase polymerization, as the electrocatalyst for HER. Theoretically, the PPy shell serves both as electron-transfer channels to accelerate electron migration, and as Mott-Schottky centre to modify the electronic structure of TiB 2. Beneficially, more improved HER performance has been achieved with the overpotential of 432 mV at 10 mA cm−2, superior to that of pristine TiB 2 (848 mV at 10 mA cm−2). Moreover, excellent stability is presented during 1000 CV cycles and 10 h constant evaluation. Our study provides a new avenue to create efficient HER electrocatalyst via conductive PPy engineering. [ABSTRACT FROM AUTHOR]