The high-pressure (HP) effect on surface-enhanced Raman spectroscopy (SERS) is a new horizon due to the importance of pressure, an external stimulus that can tune the lattice and electronic band structure of the SERS substrate and the analyte molecule. Here, we have used nano-ZIF-67 as the pressure induced (PI)-SERS substrate and R6G molecules as the analyte to explore the SERS effect in both the compression and decompression cycles. Our results demonstrate SERS signal enhancement at 0.12, 0.38 and 1.12 GPa. The initial SERS enhancement at 0.12 GPa is found to be due to inter-band transition resonance. A HP synchrotron diffraction study on the ZIF-67/R6G system illustrated an initial expansion of the ZIF-67-unit cell due to the infiltration of R6G molecules inside the pores and a structural phase transition around 0.38 GPa followed by an irreversible amorphization around 3 GPa. A significant SERS enhancement is also observed when decompressed to ambient pressure after a maximum pressure of 6.42 GPa. Although the crystal lattice seems to collapse irreversibly with HP, our Raman investigations indicated the recovery of the phonon modes upon pressure release. This observation indicates an important role of the local atomic arrangements in the SERS enhancement upon the pressure release.

Reactive dyes are widely used by the textile industry to color fabrics such as wool, cotton, and viscose. The persistence of these dyes in effluents poses significant environmental concerns due to their cytotoxic, mutagenic, and carcinogenic properties, as well as their ability to inhibit mitochondrial functions. This study presents the first-ever report on the synthesis and photocatalytic application of MgFe-LDHcal/TiO2heterojunctions for the efficient detoxification of industrial wastewater. The novel composite leverages the synergistic properties of MgFe-Layered Double Hydroxides (LDH) in their calcined form (LDHcal) and titanium dioxide (TiO2), resulting in a material with enhanced photocatalytic performance. MgFe-LDHcal provides a high surface area, strong adsorption capacity, and excellent electron mobility, while TiO2is renowned for its ability to generate reactive oxygen species under light irradiation. In this study, the MgFe-LDHcal/TiO2 heterojunction was applied directly to industrial wastewater, achieving remarkable detoxification efficiency by degrading persistent organic pollutants. The composite demonstrated superior photocatalytic activity under visible light, making it suitable for practical, large-scale industrial applications. This study focuses on the photocatalytic degradation of various reactive dyes, including Reactive Green 19, Reactive Red 120, Reactive Blue 4, and Eosin Yellow, using a nanocomposite of TiO2/MgFe-LDHcal. For the first time, the photocatalytic performance of this heterojunction material was evaluated for degradation of these reactive dyes under visible light irradiation. Remarkably, the system achieved complete dye detoxification of highly concentrated waste water within 1 hour. The heterojunction was thoroughly characterized using powder X-ray diffraction (XRD) to confirm the crystalline structure and composite formation. UV-Visible and photoluminescence (PL) spectroscopy were conducted to assess the optical properties and photocatalytic activity under light exposure. High-resolution transmission electron microscopy (HR-TEM) was used to examine particle size, interplanar spacing, and morphology. Additionally, the rejuvenation studies demonstrated that the MgFe-LDHcal/TiO2 heterojunction can be reused for multiple cycles, highlighting its potential as a sustainable and effective photocatalyst for industrial wastewater treatment.

Reactive dyes are presently the most common type of dye utilised by the garment sector to colour wool, cotton, and viscose-based clothing. By using the typical biological degradation & sediment absorb approaches, it is quite impossible to get rid of them. Thus reactive dye colors in the effluent are major environmental issues in recent times. In this work Reactive dye series has been choosen for the photocatalytic degradation studies over calcined form of TiO2 and MgFe-LDHcal nanocomposites (TiO2/MgFe-LDHcal). This work assesses, a detailed investigation of the photocatalytic degradation of the reactive class dyes Ca. Reactive green 19, Reactive red 120, Reactive blue 4 and Eosin Yellowish dye by layered double hydroxide (LDH) and TiO2 heterojunction (MgFe-LDHcal/TiO2). Here for the first time, photocatalytic application of the said heterojunction was investigated toward the degradation of the reactive dyes. As these dyes are cytotoxic, mutagenic, and inhibit certain mitochondrial functions and often are carcinogens. This heterojunction system degrades the reactive dyes in 1 hour of visible light irradiation. The said LDH heterojunction was characterised by powder XRD to confirm the phase and composite formation, Uv-Visible and PL spectra to know the optical activity of the material in presence of light. The size, interplanar spacing and morphology of the nanoparticles were inspected by HR-TEM analysis. All the batch experiments were carried out at room temperature, without any adjustment of pH, at the dye concentration varying from 20 to 50 mg/L. Furthermore, according to the rejuvenation study, the prepared LDH heterojunction system could potentially be put to use for a number of cycles.

The functionalized NiFe-LDH with photosensitized GQDs were synthesized through the hydrothermal route by differing the amount of GQDs solution and studied its efficacy towards the mineralization of textile dyes under visible light. The synthesized samples were characterized by XRD, FESEM, HRTEM, DRUV-Vis, RAMAN, XPS, and BET. The combined effect of the hexagonal carbon lattice in GQD and open layered porous structure of NiFe-LDH nanosheets results in the contraction of the lattice. Different reactive and conventional dyes were taken as representative dyes to evaluate the activity of the as-synthesized photocatalysts. The enhanced electron absorption/donor effect between GQDs and NiFe-LDH, and the growth of oxygen-bridged Ni/Fe-C moieties enable the composite to exhibit better photocatalytic activity. Both photocatalytic activity and characterization results confirmed that the GQD@NiFe-LDH nanocomposite heterostructure synthesized at 160 oC by taking 10 ml of GQDs aqueous solution named GNFLDH10 has a higher degree of crystallinity and has the best photocatalytic efficiency compared to other reported visible light catalysts. Specifically, the above optimized GQD@NiFe-LDH photocatalyst is capable of photo-mineralizing 50 ppm of Reactive Green in 20 mins, Reactive Red in 20 mins, and Congo Red in 25 mins respectively following a direct Z-scheme mechanism with substantial reusability.

The electrodeposition of manganese dioxide from purified leach liquor obtained by reduction leaching of polymetallic manganese nodules using sucrose as a reductant in H2SO4 medium followed by 2 stages purification process was described. The role of cationic additive on the morphology and electrochemical properties were investigated by using Cetyltrimethylammonium bromide (CTAB) (0-500 mg dm(-3)). The orthorhombic phase of gamma-MnO2 was confirmed from the XRD patterns of as prepared electrolytic manganese dioxide (EMD). The effect of CTAB on EMD has been investigated in terms of morphology, current efficiency (CE) and energy consumption. In addition to this, for the first time we have studied the interactions of EMD with hemoglobin (Hb). Herein, the molecular interactions between Hb and nano EMD prepared at an optimum condition were explored using various spectroscopic techniques including UV-vis absorption, fluorescence, and circular dichroism. Various quantitative parameters such as association/dissociation constants, binding cooperativity were determined to illustrate the biomolecular interactions. Our results suggest that hemoglobin remains structurally stable in the bioconjugates formed by the simple adsorption method. However, at higher temperature, hemoglobin was found to adopt an unfolded conformational state both in free form and bioconjugates. This work would be helpful in designing of safe nanoparticles (NPs) for biomedical applications.

In this work, synthesis of lithium-manganese dioxide from natural manganese (Mn) bearing resources is described. The purified nodule leach solution is taken as the potential source for the fabrication of Li-MnO2 nanocomposite (NC). Herein, we reported a simple room temperature chemical precipitation route for the synthesis of lithium-manganese dioxide NC in absence of surface directing reagent/template. Also, we investigated the molecular interactions of the prepared NCs with lysozyme (Lyz) to understand the biocompatibility of these NCs. A systematic study of the interactions between NC and biomolecule plays a key role in understanding the fate of NCs in biological applications like biosensing, imaging, and drug delivery etc. The conformational changes of Lyz in NC solutions are characterized by using circular dichmism and FTIR which revealed that the secondary structure of Lyz remains stable in presence of NCs. Moreover, we studied the activity of Lyz using Micrococcus lysodeikticus cells. The results indicate that the NC prepared at 1 M LiOH concentration showed better lysis activity as compared to NC prepared at low LiOH concentration. This work provides a simple preparation route for the synthesis of NCs from natural Mn resources and recommends the use of different NCs for further biological studies.

The synthesis of an economical and efficient photocatalyst for the fabrication of clean H-2 from water splitting is significant for the actual application. In this work, we have reported the low-cost synthesis of reduced graphene oxide embedded nickel phosphate (RGO-NiPO) photocatalyst by low-temperature hydrothermal reaction system. The composite showed great potential in the photoreduction reaction of water under visible spectrum irradiation. The morphological analysis of RGO-NiPO explains an amazing interaction between the RGO and NiPO surface which efficiently interferes with the charge carrier losses during the water reduction reaction in the presence of light. Furthermore, this phenomena was evidenced from the time-resolved photoluminescence spectra, where the decay components were calculated to have a shorter decay time (1.40 ns) in the case of 12RGO-NiPO than that of NiPO (5.3 ns), implying efficient e(-) transfer across the NiPO-RGO interface. The NiPO nanostrings were face-to-face assembled on the surface of the graphene sheet, which makes the intimate contact between the nanostrings and graphene feasible. Such noble-metal-free photocatalyst may provide an approach for the design of very efficient water-splitting catalysts, which are predicted to be applied to the actual photocatalytic water-splitting industry. Owing to the synergetic effect of the distinguishable structural and compositional privileges, the RGO-NiPO nanostrings showed admirable activity with a H-2 rate of 9000 mu mol/h/g and high photocatalytic water-splitting stability without the use of any other cocatalysts.

Graphene based materials have attracted global attention due to their excellent properties. GO-metal oxide nanocomposites have been conjugated with biomolecules for the development of novel materials and potentially used as biomarkers. Herein, a detailed study on the interaction of Bovine serum albumin (BSA) with MnO2@RGO (manganese dioxide-reduced graphene oxide) nanocomposites (NC) has been carried out. MnO2@RGO nanocomposites were prepared through a template/surfactant free hydrothermal route at 180 degrees C for 12 h by varying the graphene oxide (GO) concentration. Different biophysical experiments have been carried out to evaluate molecular interactions between BSA and NCs. Intrinsic fluorescence has been used to quantify the quenching efficiency of NCs and the binding association of BSA-NC complexes. NCs effectively quenched the intrinsic fluorescence of BSA via static and dynamic mechanism. Further, the results indicate that the molecular interactions of NC with BSA are dependent on the GO percentage in NC. Circular dichroism results demonstrate nominal changes in the secondary structure of BSA in presence of NCs. Also, the esterase-like activity of BSA was marginally affected after adsorption upon NCs. In addition, the FESEM micrographs reveal that the protein-NC complexes consist of nanorod and sheet-like morphologies are forming aggregates of different sizes sizes. We hope that this study will provide a basis for the design of novel graphene based and other related nanomaterials for several biological applications. Communicated by Ramaswamy H. Sarma

Attributable to the superior visible light active nature and high efficiency, silver phosphate (Ag3PO4) has attracted gigantic attention for decomposition of organic contaminants and fuel production. The photoresponsivity of Ag3PO4 hugely depends upon the morphology, method of fabrication, formation of hybrids and photocorrosive nature of it. The cause of high activity, activity based on morphology and various methods of synthesis of Ag3PO4 based photocatalysts to improve the stability of Ag3PO4 for applications towards energy and environment is the crux of the matter in this review. Important applications including photocatalytic pollutant degradation, O-2/H-2 production, and bacterial degradation are also addressed. Finally, summary and outlooks on the challenges and future perspectives of this emerging photocatalyst are presented.

The same copper phosphate catalysts were synthesized by obtaining the methods involving solid state as well as liquid state reactions in this work. And then the optimised p-n hybrid junction photocatalysts have been synthesized following the same solid/liquid reaction pathways. The synthesized copper phosphate photocatalyst has unique rod, flower, caramel-treat-like morphology. The Mott-Schottky behavior is in accordance with the expected behavior of n-type semiconductor and the carrier concentration was calculated using the M-S analysis for the photocatalyst. And for the p-n hybrid junction of 8RGO-Cu3(PO4)2-PA (PA abbreviated for photoassisted synthesis method), 8RGO-Cu3(PO4)2-EG(EG abbreviated for Ethylene Glycol based synthesis method), 8RGO-Cu3(PO4)2-PEG (PEG abbreviated for Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol based synthesis method)the amount of H2 synthesized was 7500, 6500 and 4500 µmol/h/g, respectively. The excited electrons resulting after the irradiation of visible light on the CB of p-type reduced graphene oxide (RGO) migrate easily to n-type Cu3(PO4)2 via. the p-n junction interfaces and hence great charge carrier separation was achieved.

This work explains about the visible light photocatalytic activities of wide band gap metal oxides (TiO2, ZnO, CeO2, Eg > 3.0 eV) after the overture of reduced graphene oxide. The reduced graphene oxide and metal oxide heterostructures (RGO-MO) Ca. RGO-TiO2, RGO-ZnO, RGO-CeO2 were synthesized through microwave, template assisted, and hydrothermal methods respectively. This explains about the activity of the photocatalysts towards hydrogen production via water splitting, water treatment towards inorganic contaminants with or without dye sensitization activity as well. RGO-MO having particle size 5-10 nm which shows great activity towards various photocatalytic activities. Pure TiO2, CeO2 and ZnO are UV active semiconductors having wide band gap 3.2 eV. However, when these semiconductors are modified with RGO they are showing better visible light activity towards photoreduction of Chromium (VI) and hydrogen production by half reaction of water.

Systematic experimental investigation of MnO2–BSA complexes in terms of the structure and stability of the protein as well as the aggregation of the nanoparticle.

Photocatalytic activity of α-MnO2 nanorod synthesized through a low temperature (90 °C) single step precipitation route in the absence of surfactant and template is reported. Dependence of precipitation time on morphology of the synthesized α-MnO2 has been investigated and the photocatalyst has been tested for the degradation of organic cationic and anionic dyes. Detailed study on the degradation of Rhodamine B (RhB) has been carried out. The lower precipitation time (of 6 h) is found to be ideal for the synthesis of the photocatalyst. The mechanism of RhB photodegradation under visible light using α-MnO2 nanorods has been established through mass spectra analysis. The intermediate products during degradation exhibits de-ethylation and mineralisation steps. Experimental results suggest that both super oxide and hydroxyl radicals are the main active species in the process. Total organic carbon (TOC) analysis of treated RhB reveals complete mineralisation. The photodegradation efficiency of α-MnO2 for cationic and anionic dyes are found to be 95–100 % under visible light irradiation. The excellent photocatalytic activity of α-MnO2 can be correlated with its 1-D morphology of high aspect ratio and low photoluminescence intensity. The complete dye discoloration within 10 min and total mineralisation of RhB in 25 min is quite significant especially under visible light irradiation and has never been reported earlier.

The Back Cover picture shows the unique visible-light-driven activity of 3 D Co3(PO4)2–reduced graphene oxide flowers towards hydrogen generation through water splitting. More details can be found in the Full Paper by Samal et al. on page 3150 in Issue 22, 2016 (DOI: 10.1002/cssc.201601214).

Photocatalytic activity of alpha-MnO2 nanorod synthesized through a low temperature (90 degrees C) single step precipitation route in the absence of surfactant and template is reported. Dependence of precipitation time on morphology of the synthesized alpha-MnO2 has been investigated and the photocatalyst has been tested for the degradation of organic cationic and anionic dyes. Detailed study on the degradation of Rhodamine B (RhB) has been carried out. The lower precipitation time (of 6 h) is found to be ideal for the synthesis of the photocatalyst. The mechanism of RhB photodegradation under visible light using alpha-MnO2 nanorods has been established through mass spectra analysis. The intermediate products during degradation ex-hibits de-ethylation and mineralisation steps. Experimental results suggest that both super oxide and hydroxyl radicals are the main active species in the process. Total organic carbon (TOC) analysis of treated RhB reveals complete mineralisation. The photodegradation efficiency of alpha-MnO2 for cationic and anionic dyes are found to be 95-100% under visible light irradiation. The excellent photocatalytic activity of alpha-MnO2 can be correlated with its 1-D morphology of high aspect ratio and low photoluminescence intensity. The complete dye discoloration within 10 min and total mineralisation of RhB in 25 min is quite significant especially under visible light irradiation and has never been reported earlier.

The design, synthesis, and photoelectrochemical characterization of Co-3(PO4)(2), a hydrogen evolving catalyst modified with reduced graphene oxide (RGO), is reported. The 3D flowerlike Co-3(PO4)(2) heterojunction system, consisting of 3D flowerlike Co-3(PO4)(2) and RGO sheets, was synthesized by a one-pot in situ photoassisted method under visible-light irradiation, which was achieved without the addition of surfactant or a structure-directing reagent. For the first time, Co-3(PO4)(2) is demonstrated to act as a hydrogen evolving catalyst rather than being used as an oxygen evolving photoanode. In particular, 3D flowerlike Co-3(PO4)(2) anchored to RGO nanosheets is shown to possess dramatically improved photocatalytic activity. This enhanced photoactivity is mainly due to the staggered type II heterojunction system, in which photoinduced electrons from 3D flowerlike Co-3(PO4)(2) transfer to the RGO sheets and result in decreased charge recombination, as evidenced by photoluminescence spectroscopy. The band gap of Co-3(PO4)(2) was calculated to be 2.35 eV by the Kubelka-Munk method. Again, the Co-3(PO4)(2) semiconductor displays n-type behavior, as observed from Mott-Schottky measurements. These RGO-Co-3(PO4)(2) conjugates are active in the visible range of solar light for water splitting and textile dye degradation, and can be used towards the development of greener and cheaper photocatalysts by exploiting solar light.

A visible light driven, direct Z-scheme reduced graphene oxide-Ag3PO4 (RGO-Ag3 PO4 ) heterostructure was synthesized by means of a simple one-pot photoreduction route by varying the amount of RGO under visible light illumination. The reduction of graphene oxide (GO) and growth of Ag3PO4 took place simultaneously. The effect of the amount of RGO on the textural properties and photocatalytic activity of the heterostructure was investigated under visible light illumination. Furthermore, total organic carbon (TOC) analysis confirmed 97.1 % mineralization of organic dyes over RGO-Ag3PO4 in just five minutes under visible-light illumination. The use of different quenchers in the photomineralization suggested the presence of hydroxyl radicals ((.)OH), superoxide radicals ((.)O2 (-)), and holes (h(+)), which play a significant role in the mineralization of organic dyes. In addition to that, clean hydrogen fuel generation was also observed with excellent reusability. The 4 RGO-Ag3PO4 heterostructure has a high H2 evolution rate of 3690 μmol h(-1)  g(-1), which is 6.15 times higher than that of RGO.