A hierarchical structure composed of vertically aligned ultrathin two dimensional (2D) MoS2/WS2 nanosheets is fabricated through a facile one-pot hydrothermal reaction. Scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence (PL) indicate that the MoS2/WS2 hybrid shows ultrathin nanoflakes with a thickness of 2–10 nm, and the as prepared heterostructure markedly enhances the separation of electro–hole pairs. Benefiting from the integrated W-doped MoS2, the vertically aligned nanostructure exhibits a moderate degree of disorder and increased active surface area. Electrochemical measurements (cyclic voltammetry (CV), linear sweep voltammetry (LSC) and electrochemical impedance spectroscope (EIS) under light illumination or in dark) indicated that the MoS2/WS2 hybrid (especially the hybrid with Mo : W of 1/1) exhibits much better photo-and electrochemical performance than its counterpart of pure MoS2 or WS2, which made it a promising photocathode for electrocatalytic hydrogen evolution reaction (HER) by photo-assistance.

The present study demonstrates the effect on photovoltaic performance of regioregular poly (3-hexylthiophene)(rr-P3HT) grafted oxide graphene (GO) on in situ doping of cadmium sulfide (CdS) quantum dots (QDs) (GO-rr-P3HT-CdS). Firstly, CH2OH-terminated rr-P3HT of different molecular weights (MW) and distributions synthesized by Grignard metathesis (GRIM) method was grafted onto carboxylic groups of GO via esterification reaction. Then, the GO-rr-P3HT-CdS was prepared with an oleylamine solution composed of 1 mmol of cadmium and 1 mmol high pure sulfur in the presence of GO-rr-P3HT. The covalent linkage and the strong electronic interaction between the rr-P3HT and graphene moieties in GO-rr-P3HT were confirmed by spectroscopic analyses (XPS and FTIR). The photovoltaic properties of as prepared nanocomposites are evaluated by UV–Vis spectroscopy, photoluminescence, and electrochemical measurements, and are found to be strongly affected by MW, which influences the behavior of the bulk heterojunction organic solar cells based on this material. It is found that the optical and electrochemical properties of the resultant GO-rr-P3HT-CdS nanocomposite are relatively better than that of conventional composite, in which the pristine graphene, CdS, and rr-P3HT (or GO-rr-P3HT) are physically mixed together. The significant PL quenching is attributed to additional decaying paths of the excited electrons through the CdS. Bulk heterojunction photovoltaic devices with a thin film of GO-rr-P3HT-CdS containing higher molecular weights of rr-P3HT show an increase in the power conversion efficiency by about three times with respect to their counterparts based on GO-rr-P3HT/CdS and GO/rr-P3HT/CdS due to improvement in contact between GO-rr-P3HT and CdS and enhancement in the device parameters like fill factor and open-circuit voltage (VOC).

•Bifunctional leaf-like CdS/MoS2 hybrids were prepared by electrodeposition.•The interactive influence of MoS2 and CdS on the catalytic activity was analyzed.•The CdS/MoS2 showed the improved photocatalytic activity due to the p–n junction.•The CdS/MoS2 has superior electrocatalytic activity for HER relative to the MoS2.•A Tafel slope of ∼42 mV/decade was measured for CdS/MoS2 hybrid in the HER.Bifunctional leaf-like CdS/MoS2 hybrids were successfully prepared by electrodeposition. The interactive influences between MoS2 and CdS on the photoelectrocatalytic activity for catalyst of CdS/MoS2 were characterized by analyzing the current density (J)–potential (V) curves of cathodic and anodic polarization. On the one hand, the CdS/MoS2 hybrid showed the improved photoelectrochemical performance which was attributed to the visible light absorption enhanced by MoS2 and the formation of p–n junction between CdS and MoS2. On the other hand, the CdS/MoS2 hybrid exhibited superior electrocatalytic activity in the hydrogen evolution reaction (HER) relative to the MoS2 catalyst. A Tafel slope of ∼42 mV/decade was measured for CdS/MoS2 hybrid in the HER, which exceeded by far the activity of previous MoS2 catalysts and resulted from the abundance of catalytic edge sites on the MoS2 nanoparticles. The Tafel slope of∼42 mV/decade suggested the Volmer_Heyrovsky mechanism for the CdS/MoS2-catalyzed HER, with electrochemical desorption of hydrogen as the rate-limiting step.

•Bifunctional CdS@MoS2 nanorod array exhibit photoelectrocatalytic activity for HER.•Nanorod array shows better photoelectrochemical activity than bilayer structure.•The photoresponse of photocathode is structure-dependent.•Photocurrent derives of the photogenerated electrons in the vertical nanorods.•Reverse biased P type enhances the depletion region, reducing charge recombination.The structure design of hydrogen electrodes catalyst is important for the photoelectrocatalytic activity for hydrogen evolution reaction (HER). An oriented nanorod array on transparent conductive substrates would be the most desirable nanostructure in preparing photoelectrocatalytic cells (PECs) because of its efficient charge separation and transport properties as well as superior light harvesting efficiency. We report a bifunctional CdS@MoS2 core–shell nanorod arrays which exhibit both photo- and electrocatalytic activity for HER. The CdS@MoS2 core–shell nanorod arrays are prepared by a simple hydrothermal method and a followed electrodeposition. The characterization results indicate that CdS nanorods are covered by the MoS2 (∼30 nm), and the as prepared heterostructure markedly improves the separation and transfer of charge carriers. The photo- and electrocatalytic activity are characterized by cathodic polarization measurement. The results show that the nanorod array exhibits much better photo- and electrochemical performance than its counterpart of bilayer structure where no photocurrent is detected, suggesting that the photoresponse of photocathode is structure-dependent. Photocurrent derives of the hopping of photogenerated electrons in the vertical direction of CdS@MoS2 nanorods where p–n junction is probably reverse biased the P region, leading to the depletion region enhanced, and thus, suppresses charge recombination. This work proposes a new idea for designing the nanostructure of cathode with enhanced electrocatalytic activity by photo-assistance.