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Schematic of photocatalytic H2 generation using Ni/SnS2 nanosheets along with the energy levels of SnS2 and Ni nanostructures.

In the present study, we have demonstrated a unique approach for the synthesis of nanostructured ternary metal sulphides, XIn2S4 (X = Cd, Zn), using a simple, template free and low temperature solid phase reaction. A stoichiometric amount of precursors including CdO/ZnO, In2O3 and thiourea were mixed homogeneously and heated at 150 °C for different time intervals to produce nanostructured XIn2S4. Various molar ratios of the precursors were tried and among the different ratios, the molar ratio of 1 : 1 : 8 was found to be optimum for the growth of phase pure nano crystalline XIn2S4. X-ray analysis confirms the formation of cubic spinel Cadmium Indium Sulfide (CdIn2S4) and hexagonal Zinc Indium Sulfide (ZnIn2S4). HRTEM analysis confirms the formation of nanostructures of XIn2S4 with spherical and rod like mixed morphology. The band gap of the as synthesized materials is within the visible region i.e. 2.25 and 2.6 eV for CdIn2S4 and ZnIn2S4, respectively. Therefore, the activity of both the photocatalyts was tested for hydrogen generation by H2S and H2O splitting under natural solar light. The ZnIn2S4 photocatalyst was found to be more active for both H2S and H2O splitting reactions with H2 evolution rates of 6994 μmol h−1 g−1 and 243 μmol g−1, respectively, whereas for CdIn2S4 the rates were found to be 6128 μmol h−1 g−1 and 128.4 μmol g−1, respectively. The H2 evolution rate by H2S splitting was found to be much higher than various previously reported nanostructured photocatalysts. The simple, environmentally friendly and cost effective method reported herein can be applied for the large scale synthesis of XIn2S4 nanoparticles, which is the novelty of the present work.

One-pot green synthesis of propargylamines using ZnCl2 loaded TiO2 nanomaterial under solvent-free conditions has been effectively accomplished. The aromatic aldehydes, amines, and phenylacetylene were reacted at 100 °C in the presence of the resultant catalyst to form propargylamines. The nanocrystalline TiO2 was initially synthesized by a sol–gel method from titanium(IV) isopropoxide (TTIP) and further subjected to ZnCl2 loading by a wet impregnation method. X-ray diffraction (XRD) patterns revealed the formation of crystalline anatase phase TiO2. Field emission scanning electron microscopy (FESEM) showed the formation of agglomerated spheroid shaped particles having a size in the range of 25–45 nm. Transmission electron microscopy (TEM) validates cubical faceted and nanospheroid-like morphological features with clear faceted edges for the pure TiO2 sample. Surface loading of ZnCl2 on spheroid TiO2 nanoparticles is evident in the case of the ZnCl2 loaded TiO2 sample. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ti4+ and Zn2+ species in the ZnCl2 loaded TiO2 catalyst. Energy-dispersive X-ray (EDS) spectroscopy also confirmed the existence of Ti, O, Zn and Cl elements in the nanostructured catalyst. 15% ZnCl2 loaded TiO2 afforded the highest 97% yield for 3-(1-morpholino-3-phenylprop-2-ynyl)phenol, 2-(1-morpholino-3-phenylprop-2-ynyl)phenol and 4-(1,3-diphenylprop-2-ynyl)morpholine under solvent-free and aerobic conditions. The proposed nanostructure-based heterogeneous catalytic reaction protocol is sustainable, environment-friendly and offers economic viability in terms of recyclability of the catalyst.

Developing stable semiconducting oxides that are active in the visible region for photocatalytic reactions is a major technological challenge. Herein, we report a facile co-precipitation based synthesis of PbCrO4 nanostructures with the aim to study their hitherto unreported hydrogen production potential. It has been observed that monoclinic PbCrO4 nanorods have been generated using a simple co-precipitation method in the presence of water and methanol as solvents while spherical nanostructures are produced using an ultrasonication assisted co-precipitation method. The nanorods synthesized by the aqueous co-precipitation method have yielded the highest rate of hydrogen production (3214 μmol h−1 0.5 g−1) by splitting hydrogen sulfide (H2S) gas.