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Ultrasonic spray pyrolysis is a superior method for preparing and synthesizing spherical particles of metal oxide or sulfide semiconductors. Cadmium sulfide (CdS) photocatalysts with different sizes and doped-CdS with different dopants and doping levels have been synthesized to study their properties of photocatalytic hydrogen production from water. The CdS photocatalysts were characterized with scanning electron microscopy (SEM), X-ray fluorescence-spectrometry (XRF), UV-Vis absorption spectra and X-ray diffraction (XRD) to study their morphological and optical properties. The sizes of the prepared CdS particles were found to be proportional to the concentration of the metal nitrates in the solution. The CdS photocatalyst with smaller size showed a better photocatalytic activity. In addition, Cu doped CdS were also deposited and their photocatalytic activities were also investigated. Decreased bandgaps of CdS synthesized with this method were found and could be due to high density surface defects originated from Cd vacancies. Incorporating the Cu elements increased the bandgap by taking the position of Cd vacancies and reducing the surface defect states. The optimal Cu-doped level was found to be 0.5 mol % toward hydrogen evolution from aqueous media in the presence of sacrificial electron donors (Na₂S and Na₂SO₃) at a pH of 13.2. This study demonstrated that ultrasonic spray pyrolysis is a feasible approach for large-scale photocatalyst synthesis and corresponding doping modification.

Controlled synthesis of two-dimensional noble metal nanomaterials with an in-plane branching morphology has been of great research interest recently, but has so far achieved limited success for AuAg-based nanocrystals. Herein, we report the fabrication of gold–silver (AuAg) nanosheets with abundant in-plane cracking and sub-10 nm thickness via one-pot kinetics-controlled synthesis. In particular, the dropwise addition of Au/Ag precursor solutions into a mixture of octadecyltrimethylammonium chloride and ascorbic acid, kept in an ice–water bath, leads to the formation of nanobelts/nanowires initially, followed by their growth into branched nanosheets. These AuAg products can further convert to AuAgM (M = Pd or Pt) nanosheets via galvanic replacement reaction under ambient conditions. Interestingly, the AuAgPd nanosheets are obtained with a Au@PdAg core–shell elemental distribution with many zigzag edges. In contrast, the AuAgPt nanosheets show a homogeneous distribution of all three metals, together with a highly stippled surface. All these AuAg-based nanosheets exhibit strong absorbance in the near-infrared region and thus show superb activities as photocatalysts for UV-vis light-assisted reduction of 4-nitrophenol due to the effect of plasmon enhancement. The present study provides a feasible route to generating AuAg-based multimetallic nanocrystals with a two-dimensional structure, in-plane branching morphology, and effective control over the elemental distribution, which could be potentially extended to other noble metals and/or alloys for the rational design of plasmonic photocatalysts. [ABSTRACT FROM AUTHOR]

Wavy gold@palladium-gold (Au@PdAu) core-shell nanoplates are successfully prepared via seeded growth. Starting with the use of plate-like Au nanocrystals with the thickness of ~10 nm as seeds, the preferential deposition of Pd atoms vertical to the upper/bottom surface plane allows the formation of the core-shell structure with tunable thickness, where the shell thickness can be limited to sub-10 nm. As confirmed by X-ray diffraction (XRD) analyses, further atomic diffusion allows the generation of PdAu alloy phase in the products, leading to the formation of Au@PdAu core-shell nanostructure. With the strong absorbance in near-infrared (NIR) region, they could work as efficient catalysts towards reduction of 4-nitrophenol under visible light irritation. In particular, the enhancement factor (the ratio of apparent rate constant in light to that in dark) reaches as high as 6.76 arising from the plasmonic-enhancement effect. The current work provides a feasible strategy to fabricate Pd-based bimetallic nanocrystals with plasmonic properties and validates their promising application in the plasmonic-enhanced catalysis. [ABSTRACT FROM AUTHOR]

Strontium titanate (SrTiO3) is one of the most promising photocatalysts for overall water splitting (OWS). Strains can be commonly introduced in SrTiO3 during the synthetic processes, for example, in pulsed laser deposition. However, the effect of the strains on the catalytic performance of OWS is still unclear to date. Herein, first-principles calculations were performed to evaluate the impact of biaxial strains applied in SrTiO3 (001) surface on the oxygen evolution reaction (OER), the bottleneck of OWS. It was found that the applied strains, especially the compressive strains, significantly affect the free energy changes for H2O dissociation and *OOH deprotonation of OER on SrTiO3 (001). More interestingly, the tensile strains reduce the surface energy and lower the OER overpotential through reducing the free energy change for the rate-determining step, i.e., the second step of OER (*OH deprotonation), while the compressive strains increase the surface energy and the OER overpotential. Consequently, it is probable to introduce the tensile strains in the synthetic process to enhance the OER performance on SrTiO3 (001) surface. [ABSTRACT FROM AUTHOR]

Abstract: Ni2+ doped Cd1−x Zn x S microsphere photocatalysts were prepared by a new hydrothermal method. Experimental results showed that the doped Ni2+ can not only affect the crystal structure and morphology of Cd1−x Zn x S photocatalysts, but also greatly improve its photocatalytic activity. It was found that 0.1wt% Ni2+ doped Cd0.1Zn0.9S photocatalyst showed the highest activity with the apparent quantum yield of 15.9% at 420nm. The reason for the positive effects of Ni2+ was discussed. [Copyright &y& Elsevier]

This work provides a molecular scale insight into non-phosgene synthesis based on the reaction of dimethylhexane-1,6-dicarbamate from 1,6-hexamethylenediamine, urea and methanol with computational electronic method. By exploring almost all possible reaction modes and comparing the effective barrier of each channel, this work analyzes the optimal reaction mechanism for both non-catalytic and self-catalytic systems. The mechanism without catalysis has a high effective free energy barrier (FEB) of 47.0 kcal mol−1. As for self-catalytic system, after sorting out the reaction pathway network, an effective FEB of 24.6 kcal mol−1 is confirmed which corresponds to dissociation of urea. [Display omitted] • A molecular scale insight into synthesis of carbamate from amine, urea and methanol. • Almost exhaustive potential energy surface exploration. • The optimal pathway involves self-catalysis. • Carbamimidic acid, isomer of urea, has good catalytic effect. • The whole process is determined by dissociation of urea. [ABSTRACT FROM AUTHOR]

Polyhedral AuAgPd nanoframes are successfully prepared via a stepwise synthesis, exhibiting noteiceable enhancement in catalytic activity for reduction of 4-nitrophenol under UV–vis light irradiation. [Display omitted] • AuAgPd nanoframes were prepared with a polyhedral morphology. • They showed a broad and strong absorption over the visible range. • Enhanced catalytic activity was achieved under UV–vis light irradiation. AuAgPd polyhedral nanoframes (PNFs) are prepared via stepwise synthesis and exhibit a strong and broad absorption covering the visible region. For 4-nitrophenol reduction, noticeable enhancement in catalytic efficiency is observed upon UV–vis light irradiation, confirming the structural advantages in plasmonic harvesting. [ABSTRACT FROM AUTHOR]

Discovering an active and durable catalyst for oxygen reduction reaction is crucial to the commercialization of fuel cells, but remains grand challenging. Here we report, for the first time, the trace doping of early transition metal (ETM) Re into ultrathin PtNiGa nanowires (Re-PtNiGa NWs) to construct a novel catalyst integrating the superior activity, long-time durability, and high utilization efficiency of Pt atoms. Impressively, the Re-PtNiGa tetrametallic NWs present a 19.6-fold enhancement in mass activity (3.49 A mg−1 Pt) compared to commercial Pt/C catalyst and only a 10.6% loss in mass activity after 20,000 cycles of durability test. Moreover, the real fuel cell assembled by Re-PtNiGa NWs on the cathode strongly supports its great potential in fuel cells. The density functional theory calculations reveal that introduction of ETM Re into PtNiGa NWs could weaken binding strength of oxygenated species and elevate dissolution potential, well rationalizing the great enhancements in activity and durability. [Display omitted] • The trace doping of early transition metal Re into ultrathin PtNiGa nanowires to construct a novel catalyst was reported. • Ultrathin Re-PtNiGa NWs presented a 19.6-fold enhancement in mass activity(3.49 A mg−1 Pt) compared to commercial Pt/C. • The H 2 -O 2 PEMFC assembled by Re-PtNiGa NWs delivered a negligible decay (4.9%) of the output current density for 100 h. • This study revealed that doping of Re could weaken binding strength of oxygenated species and elevate dissolution potential. [ABSTRACT FROM AUTHOR]