Effect of synthesis methods on the activity of NiO/Co3O4 as an electrode material for supercapacitor: in the light of X-ray diffraction study.

The formation of heterostructures by combining individual components (NiO and Co3O4) is a preferred approach to enhance electrochemical performance as it leads to improved charge transfer and surface reaction kinetics. In the present work, a NiO/Co3O4 composite was prepared by two methods. First, neat NiO and Co3O4 were prepared by adopting the hydrothermal method followed by the formation of the composite (i) by a hydrothermal route (NC-Hydro) and (ii) by a calcination route (NC-Cal). NC-Hydro composite shows a specific capacity of 176 C g-1 at 1 A g-1 of current density in the three-electrode system in a 2 M KOH solution as an electrolyte with 90% cyclic retention after 5000 cycles at 4 A g-1. NC-Cal shows a specific capacity of 111 C g-1 at 1 A g-1 with 75% cyclic retention. The coulombic efficiency of NC-Hydro was 86.3% while for NC-Cal it was 42.3%. The reason behind the superior electrochemical performance of NC-Hydro in comparison to NC-Cal may be the large interlayer spacing and lattice parameters of the former, which provide large space for redox reactions. The unit cell volume of the composites was more than that of the constituents. This study reveals that the composites prepared by the hydrothermal method have superior electrochemical properties in comparison to composites prepared by the calcination method.

A facile in situ approach to fabricate N,S-TiO2/g-C3N4 nanocomposite with excellent activity for visible light induced water splitting for hydrogen evolution.

A series of novel N,S-TiO2/g-C3N4 nanocomposite (abbreviated as TuT) photocatalysts has been synthesized via a facile, cost effective, in situ thermal induced polymerization method. The as-synthesized nanocomposites were thoroughly characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-Vis DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photo luminescence spectroscopy (PL). Using UV-Vis DRS, a gradual enhancement in visible light absorption towards the red end was observed for the xTuT photocatalyst in comparison to bare g-C3N4 (Tu). The result demonstrates that thermal reaction of a higher wt% of thiourea with respect to Ti precursor causes coupling of the N,S-TiO2 and g-C3N4 nanocomposite, however at a lower wt% only N,S-TiO2 forms. The photocatalytic activity has been evaluated through H2 evolution. The synergistic combination of small crystallite size, the crystalline anatase phase, enhanced visible light absorption ability, enhanced specific surface area and the effective charge separation properties of the 10TuT photocatalyst makes the system pivotal for photocatalytic H2 evolution under visible light irradiation.

Plasmon induced nano Au particle decorated over S,N-modified TiO(2) for exceptional photocatalytic hydrogen evolution under visible light.

Nano Au deposited mesoporous S,N-TiO2 (SNT) nanocomposites have been fabricated through deposition precipitation technique by employing urea as the hydrolyzing agent. To investigate the structural, optical, and electronic properties, the photocatalysts are characterized through X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoelectrochemical measurements. Here in addition to the co-catalyst nature of nano Au particles, surface plasmon resonance (SPR) effect in visible region enhances the light harvestation ability as well as transfer electrons to the conduction band of SNT. Furthermore, easy channelization of photogenerated charge carriers through sulfate facilitated redox couple makes the system more potential towards H2 evolution. TEM study exhibits well interconnective morphology in the matrix which helps easy channelization of electrons in the SNT nanocomposites. The photocatalytic activities have been evaluated for hydrogen generation under the irradiation of visible light and an enhanced activity has been observed for the Au promoted SNT due to the presence of nano Au particles, that is, 3.5 nm. The hydrogen generation activity of 3Au-SNT is nearly 9 times higher than that of neat SNT, and the energy conversion efficiency was found to be 17.6 %.