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The hybrid structure of nanoparticles (NPs) with nanosheets has the advantage of both anisotropic properties of NPs and large specific surface areas of nanosheets, which is desirable for many technological applications. In this study, MgCrO spinel NPs decorated on highly porous MgO nanosheets forming MgO/MgCr O( x) nanocomposites were synthesized by a one pot coprecipitation method followed by a heat treatment process of the solvated wet gel of MgCr-LDH with polar solvent N, N-dimethylformamide (DMF) at 400 °C. This novel synthetic methodology generates materials consisting of porous metal oxides nanosheets adhered with spinel phase NPs due to the slow generation of gases such as HO, CO, and NH under moderate temperature during the heat treatment process. The synergistic effect of much wider band gap MgO nanosheets and narrow band gap MgCrO NPs added increased stability due to the stronger bonding coordination of MgCrO NPs with MgO nanosheets. The obtained MgO/MgCr O( x) nanocomposites possess large specific surface areas, highly porous structure, and excellent interface between MgCrO NPs and MgO nanosheets, which proved from N sorption isotherm, TEM, HR-TEM study. With metallic ratio of MgCr3:1, MgO/MgCrO(MgCr3:1) nanocomposites exhibit highest H evolution rate of 840 μmolg2h, which was 2 times higher than that of pure MgCrO(420 μmolg2h). The LSV measurement study of MgO/MgCrO (MgCr3:1) nanocomposite shows an enhancement of light current density of 0.22 μA/cm at potential bias of -1.1 V. The Mott-Schottky analysis suggested the band edge positions of the n-type constituents and formation of n-n type heterojunctions in MgO/MgCrO (MgCr3:1) nanocomposite, which facilitates the flow of charge carriers. The EIS and Bode phase plot of MgO/MgCrO (MgCr3:1) nanocomposite signifies the lower interfacial charge transfer resistance and higher lifetime of electrons (2.7 ms) for enhanced H production. Lastly, the enhanced photocatalytic H production activity and long-term stability of MgO/MgCrO(MgCr3:1) could be attributed to maximum specific surface area, porous structure, close intimacy contact angle between two cubic phases of MgCrO NPs and MgO nanosheets, abundant oxygen vacancies sites, reduced charge transfer resistance and suitable band edge potential to drive the thermodynamic energy for H production. This work highlighted an effective strategy for the synthesis of cost-effective 2D porous heterojunctions nanocomposite photocatalyst for promising applications in the field of clean H production utilizing abundant solar energy.

The one-dimensional (1D) mesoporous and interconnected nanoparticles (NPs) enriched composite CoO-CuO nanofibers (NFs) in the ratio Co:Cu = 1/4 (CoO-CuO NFs) composite have been synthesized by electrospinning and calcination of mixed polymeric template. Not merely the mesoporous composite CoO-CuO NFs but also single mesoporous CoO NFs and CuO NFs have been produced for comparison. The choice of mixed polymer templates such as polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) for electrospinning is responsible for the formation of 1D mesoporous NFs. The HR-TEM result showed evolution of interconnected nanoparticles (NPs) and creation of mesoporosity in all electrospun NFs. The quantum confinement is due to NPs within NFs and has been proved by the surface-enhanced Raman scattering (SERS) study and the UV-vis-NRI diffuse reflectance spectra (DRS). The high intense photoluminescence (PL) spectra showing blue shift of all NFs also confirmed the quantum confinement phenomena. The lowering of PL spectrum after mixing of CuO in CoO nanofibers framework (CoO-CuO NFs) proved CuO as an efficient visible light response low cost cocatalyst/charge separator. The red shifting of the band gap in composite CoO-CuO NFs is due to the internal charge transfer between Co to Co and Cu, proved by UV-vis absorption spectroscopy. Creation of oxygen vacancies by mixing of CuO and CoO also prevents the electron-hole recombination and enhances the photocatalytic activity in composite CoO-CuO NFs. The photocurrent density, Mott-Schottky (MS), and electrochemical impedance spectroscopy (EIS) studies of all NFs favor the high photocatalytic performance. The mesoporous composite CoO-CuO NFs exhibits high photocatalytic activity toward phenolic compounds degradation as compared to the other two NFs (CoO NFs and CuO NFs). The kinetic study of phenolic compounds followed first order rate equation. The high photocatalytic activity of composite CoO-CuO NFs is attributed to the formation of mesoporosity and interconnected NPs within NFs framework, quantum confinement, extended light absorption property, internal charge transfer, and effective photogenerated charge separations.

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The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

h i g h l i g h t sMesoporous ZrO 2 -MCM-41synthesized by in situ incorporation process. CuO@ZM-41 synthesized by modification of CuO onto the ZrO 2 -MCM-41. CuO@ZM-41nacomposite shows semiconductor behavior and mesoporosity. High surface area, lower e À and h + recombination are enhancing the photo-reduction. g r a p h i c a l a b s t r a c tMesoporous nanocomposite (CuO@ZM-41) is synthesized by incorporating mesoporous ZrO 2 (Z) into MCM-41 (M-41) framework followed by loading of CuO by wetness impregnation method. The synergism between CuO and the support material mesoporous ZM-41 and efficient light absorption on the surface of the composite is the key factor for the reduction Cr 6+ to Cr 3+ within 30 min time. a b s t r a c tMesoporous nanocomposites of CuO/ZrO 2 -MCM-41 (CuO@ZM-41) was designed by incorporating mesoporous ZrO 2 (Z) into the high surface area MCM-41 (M-41) framework followed by loading CuO by wetness impregnation method keeping Si/Zr ratio 10. The nanocomposites were studied under PXRD, N 2 sorption, DRS spectra, FTIR, XPS, NMR, HRTEM and PL to evaluate structural, morphological, optical properties and also the mesoporosity nature of the samples. The photo-reduction of Cr 6+ was performed over CuO@ZM-41 by varying pH, substrate concentration, and irradiation time and catalyst dose. Among all the catalysts, 2 CuO@ZM-41 was found to be efficient photocatalyst for the photo-reduction of Cr 6+ . Nearly 100% reduction of Cr 6+ has been achieved by 2 CuO@ZM-41 within 30 min. Intra-particle mesoporosity, high surface area, presence of CuO nanorods and electron transfer properties are the key factors for enhancing the photo-reduction activity of 2CuO@ZM-41.

A series of Fe(II)/meso-Al 2 O 3 catalysts was prepared by the wetness impregnation method using ferrous sulfate and mesoporous alumina. Mesoporous alumina was synthesized at pH 6 by the precipitation method using aluminum isopropoxide as the aluminum source and sucrose as the template. These catalysts were characterized by different techniques such as SEM, XRD, XPS, FTIR spectroscopy, and BET surface area analysis. The catalytic activities in phenol degradation by the photo-Fenton reaction were evaluated. The effects of H 2 O 2 concentration, pH, and additive (ethanol) on the photo-Fenton reaction were studied. The sample with 0.25 wt % Fe(II)/meso-Al 2 O 3 -6 was found to be an efficient catalyst, showing 98% degradation of 2.1 × 10 -5 mol of phenol at pH 6 in 1 h.