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Nano-network Ru with definite lattice defects on amorphous Co nanosheets is obtained for the first time. Amorphous Co support can promote the surface Ru to obtain special morphology and modified electronic structure, thus improving HER activity in alkaline solution. A current density of 10 mA cm−2 can be obtained only with an overpotential of 33.5 mV. [ABSTRACT FROM AUTHOR]

An obvious H-UPD for a nano AuTiO2−x composite has been found for the first time in terms of the electrochemical characteristics of the Au composite. The electronic effect between Au and TiO2 and the oxygen vacancy defect would change the adsorption energy of H and HER activity. The HER activity of the AuTiO2−x electrode is 6.44 times that of the Au electrode. [ABSTRACT FROM AUTHOR]

The development of highly active and long-term stable electrocatalysts for the hydrogen evolution reaction (HER) is very important. Because of the hysteresis phenomenon, IrO2 is rarely used as a cathode material for the HER. Herein, an IrO2–TiO2 composite oxide was prepared using the thermal decomposition method. The physical and electrochemical characterization of the materials was achieved by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the process of the HER, the current of IrO2 is only 1.91 mA cm−2@−0.2 V in the first segment scan. However, at the 51, 101 and 151 segment scan, the HER current increases to 6.85, 15.7 and 18.2 mA cm−2@−0.2 V, respectively. During the activation process of IrO2, the HER current has increased ten times. Compared with the HER activity of IrO2, there is almost no hysteresis for the IrO2–TiO2 electrode. In the first segment scan, the HER current has already reached 27.9 mA cm−2@−0.2 V and further increased to 31.1, 33.1 and 35.0 mA cm−2 at the 51, 101 and 151 segment scan. The difference between them is not significant, which means that the IrO2–TiO2 electrode does not need activation. The IrO2–TiO2 electrode has exhibited a higher HER activity than the IrO2 electrode, which may be attributed to the electronic structure modification and the increase of the electrochemical area. [ABSTRACT FROM AUTHOR]

Hydrogen is an important renewable energy source. Electrochemical decomposition of water for hydrogen production has attracted more and more attention as an appealing hydrogen production strategy. Previous studies have proved that controlling the morphology of Ru can improve hydrogen evolution reaction (HER) activity. Therefore, the preparation of ordered spherical ruthenium nanocatalysts by hydrothermal method (Ru-HT) is described in this paper. The morphology, crystal structure and electronic state of Ru-HT were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). At the same time, the electrochemical properties and surface charge were studied and analyzed by cyclic voltammetry (CV) characterization and electrochemical impedance spectroscopy (EIS). The experimental results have demonstrated that the HER activity of Ru-HT is obviously better than that of Ru by liquid phase reduction method (Ru-LR). When HER current density reaches 10 mA cm−2, the overpotential of Ru-LR electrocatalyst is 88.8 mV, while the overpotential of Ru-HT electrocatalyst is reduced to 55.7 mV in acidic medium. The Tafel slope of Ru-HT is only 36.5 mV dec−1 and the exchange current density is 0.44 mA cm−2, which indicates the rate determining step of the HER process should be the electrochemical desorption step (Heyrovsky step). By adjusting hydrothermal time and hydrothermal temperature, HER activity was further optimized. During the optimization process, the preparation conditions would change the hydrogen adsorption intensity on Ru surface to some extent. The adsorption strength of Ru H, together with the electrochemical surface area, will affect the HER activity of Ru. Unlabelled Image • The HER activity of Ru-HT is obviously better than that of Ru-LR. • The rate determining step of the HER process for Ru-HT should be the electrochemical desorption step. • The adsorption strength of Ru-H will affect the HER activity of Ru-HT together with the ESA. [ABSTRACT FROM AUTHOR]

Electrolyzing water is an environmentally friendly and renewable way to obtain high purity hydrogen. Ruthenium has strong water dissociation ability and suitable hydrogen adsorption energy, so it is considered as one of the candidates of excellent electrocatalysts for hydrogen evolution in alkaline solution. The dynamic hydrogen bubble template (DHBT) is a good electrodeposition technology, which can obtain the 3D metal foams. However, as far as we know, there is no report on the preparation of Ru electrocatalyst by the DBHT method. In this work, the trumpet-shaped Ru on amorphous cobalt support (T-Ru/a-Co) is prepared by the DHBT electrodeposition for the first time. The defect locations are uniformly distributed on the surface of amorphous cobalt (a-Co), which can effectively lead to the formation of nano-bubble template in the DHBT process. However, this special morphology cannot be obtained on the surface of crystalline Co (c-Co). In addition, the electronic structure of T-Ru/a-Co has also been obviously modified, in which the proportion of Ru4+/Ru0 in T-Ru/a-Co has increased, accompanied by the change of binding energy of Ru. It only needs an overpotential of 49 mV to obtain a current density of 10 mA cm−2 for the T-Ru/a-Co. The specific activity (SA), turnover frequency (TOF) and mass activity (MA) of T-Ru/a-Co are 0.23 mA cm−2, 0.48 s−1 and 0.24 A mg−1, which are both higher than those of Pt/C, the disk-shaped Ru on the c-Co support (D-Ru/c-Co) and Ru/C, respectively. • The trumpet-shaped Ru is prepared by the dynamic hydrogen bubble template (DHBT) electrodeposition for the first time. • The amorphous Co can form nano-bubble template in DHBT process, but it can't be realized on the surface of crystalline Co. • The electronic structure of trumpet-shaped Ru has also been obviously modified. • The specific activity, turnover frequency and mass activity of trumpet-shaped Ru are both higher than those of Pt/C. [ABSTRACT FROM AUTHOR]

The MoS 2 /ZnIn 2 S 4 composites with MoS 2 anchored on the surface of ZnIn 2 S 4 microspheres were fabricated by a facile solvothermal method. To clarify the crystal phases, morphologies, chemical compositions, optical properties, and special surface areas of the obtained photocatalysts, the corresponding characterization measurements were performed. The photocatalytic H 2 evolution activities of MoS 2 /ZnIn 2 S 4 composites were evaluated and compared with using lactic acid as sacrificial reagents. The results showed that integrating MoS 2 with ZnIn 2 S 4 could remarkably boost the photocatalytic H 2 evolution performance and the maximum H 2 evolution rate of 201 μmol h −1 was achieved over 1 wt% MoS 2 loading on the ZnIn 2 S 4 , corresponding to the apparent quantum efficiency (AQE) about 3.08% at 420 nm monochromatic light. The photoelectrochemical tests and photoluminescence spectra (PL) versified that the efficient charge transfer and separation were achieved over MoS 2 /ZnIn 2 S 4 composite in contrast with single ZnIn 2 S 4 , which would significantly benefit the enhancement of photocatalytic H 2 activity. This work provides a desired strategy to design and synthesize the visible-light-response photocatalysts with MoS 2 as cocatalysts to enhance the photocatalytic activity. [ABSTRACT FROM AUTHOR]