Recent development of organic-inorganic hybrid photocatalysts for biomass conversion into hydrogen production.

Over the last few years, photocatalysis using solar radiation has been explored extensively to investigate the possibilities of producing fuels. The production and systematic usage of solar fuels can reduce the use of fossil-based fuels, which are currently the primary source for the energy. It is time for us to exploit renewable sources for our energy needs to progress towards a low-carbon society. This can be achieved by utilizing green hydrogen as the future energy source. Solar light-assisted hydrogen evolution through photocatalytic water splitting is one of the most advanced approaches, but it is a non-spontaneous chemical process and restricted by a kinetically demanding oxidation evolution reaction. Sunlight is one of the essential sources for the photoreforming (PR) of biomass waste into solar fuels, or/and lucrative fine chemicals. Hydrogen production through photoreforming of biomass can be considered energy neutral as it requires only low energy to overcome the activation barrier and an alternate method for the water splitting reaction. Towards the perspective of sustainability and zero emission norms, hydrogen production from biomass-derived feedstocks is an affordable and efficient process. Widely used photocatalyst materials, such as metal oxides, sulphides and polymeric semiconductors, still possess challenges in terms of their performance and stability. Recently, a new class of materials has emerged as organic-inorganic hybrid (OIH) photocatalysts, which have the benefits of both components, with peculiar properties and outstanding energy conversion capability. This work examines the most recent progress in the photoreforming of biomass and its derivatives using OIHs as excellent catalysts for hydrogen evolution. The fundamental aspects of the PR mechanism and different methods of hydrogen production from biomass are discussed. Additionally, an interaction between both composite materials at the atomic level has been discussed in detail in the recent literature. Finally, the opportunities and future perspective for the synthesis and development of OIH catalysts are discussed briefly with regards to biomass photo-reforming.

Synthesis of AuNPs@RGO nanosheets for sustainable catalysis toward nitrophenols reduction.

A facile, green and one-pot synthesis strategy for the convenient preparation of well-dispersed gold nanoparticles (AuNPs) decorated reduced graphene oxide (RGO) without using any other toxic chemicals and reductants is reported herein. The synthesized AuNPs@RGO hybrid nanomaterials were characterized by UV-visible absorption spectroscopy, FT-IR, XRD, Raman, SEM, TEM and EDX analysis. The AuNPs@RGO acts as an efficient catalyst for the reduction of organic nitroaromatics (2- & 4-nitro phenols) in the presence of NaBH4. This newly synthesized hybrid AuNPs@RGO has superior catalytic activity over any other Au-nanomaterials ever reported. The rate of nitro aromatics reduction is found to be dependent on concentrations of substrate, reductant and catalyst. The mechanisms for the synthesis and catalytic reduction have been studied and discussed.

A new analytical device incorporating a nitrogen doped lanthanum metal oxide with reduced graphene oxide sheets for paracetamol sensing.

The novel N-CeO2 nanoparticles decorated on reduced graphene oxide (N-CeO2@rGO) composite has been synthesized by sonochemical method. The characterization of as prepared nanocomposite was intensely performed by UV-Vis, FT-IR, EDX, FE-SEM, HR-TEM, XRD, and TGA analysis. The synthesized nanomaterial was further investigated for its selective and sensitive sensing of paracetamol (PM) based on a N-CeO2@rGO modified glassy carbon electrode. A distinct and improved reversible redox peak of PM is obtained at N-CeO2@rGO nanocomposite compared to the electrodes modified with N-CeO2 and rGO. It displays a very good performance with a wide linear range of 0.05-0.600 µM, a very low detection limit of 0.0098 µM (S/N = 3), a high sensitivity of 268 µA µM-1 cm-2 and short response time (<3 s). Also, the fabricated sensor shows a good sensibleness for the detection of PM in various tablet samples.

New Electrochemical Sensor Based on a Silver-Doped Iron Oxide Nanocomposite Coupled with Polyaniline and Its Sensing Application for Picomolar-Level Detection of Uric Acid in Human Blood and Urine Samples.

A simple and very sensitive electrochemical sensor for the detection of uric acid (UA) has been developed based on polyaniline (PANI) merged into a silver-doped iron oxide (Ag-Fe2O3) nanocomposite-modified glassy carbon electrode. The synthesized ternary composite material (Ag-Fe2O3@PANI) was characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray, High-resolution transmission electron microscopy, X-ray diffraction, and thermo gravimetric analysis analyses. The nanocomposite-modified electrode shows an exceptional electrocatalytic activity and reversibility to the oxidation of UA in a 0.1 M phosphate buffer solution (pH 7.0) compared to those in PANI and Ag-Fe2O3. The detection limit of UA is found to be 102 pM with a linear dynamic range of 0.001-0.900 µM. The fabricated UA sensor also exhibits good selectivity, reproducibility, and long-time stability. The limit of detection and linear range attained for the synthesized composite are much greater compared to those of any other composite materials reported in the literature. The proposed method has been successfully applied for the selective detection of UA in various real samples such as human serum and urine with good recoveries. This platform that assimilates such electrocatalytic ternary nanocomposite with high performance can be widely employed for fabricating diverse sensors.

A novel photocatalytically active mesoporous metal-free PPy grafted MWCNT nanocomposite.

A new mesoporous metal-free functionalized multi-walled carbon nanotube (f-MWCNT) covalently grafted polypyrrole (PPy) nanocomposite has been synthesized via chemical oxidative polymerization method keeping different weight ratio of f-MWCNT (1-4). Various instrumentation techniques such as UV-DRS, FT-IR, XRD, Raman, TGA, BET and TEM were used to characterize the as-prepared nanocomposite. The successfully constructed photocatalytically active mesoporous metal-free PPy grafted MWCNT nanocomposite was employed for the decontamination of nitrobenzene (NB). Among all the catalysts, f-MWCNT-PPy (3) is found to be efficient due to a large specific surface area and high pore volume by which 99.9% reduction has been achieved within 60 min. The obtained mesoporous, covalently grafted and synergistic f-MWCNT-PPy can be used as an efficient and recyclable photocatalyst for the degradation of organic contaminants from wastewater. Also, study of this kind will undoubtedly expedite new researches on solar-driven water splitting.

Efficacious separation of electron-hole pairs in CeO2-Al2O3 nanoparticles embedded GO heterojunction for robust visible-light driven dye degradation.

Herein, we have developed a facile and one pot synthesis of ternary CeO2-Al2O3@GO nanocomposite via wet chemical method. The structural and morphological characteristics of the synthesized nanocomposite was investigated using UV-DRS, FT-IR, XRD, FE-SEM, HR-TEM, EDX and TGA analysis. The CeO2-Al2O3@GO composite was tested for its ability to photocatalytically degrade Rhodamine B (RhB) under visible light illumination. The influence of various operational parameters such as pH, catalyst dosage and initial dye concentration on the photo degradation was investigated in detail. The synthesized CeO2-Al2O3@GO composite shows greater photocatalytic degradation of RhB (99.0%) under visible light irradiation than the raw CeO2, Al2O3, and GO catalysts and any other reported nanocomposite materials. The recyclability results also demonstrate the excellent stability and reusability of the CeO2-Al2O3@GO nanocomposite. This work will be beneficial in the field of industrial and engineering applications in the degradation of organic pollutants. Also, a study of this kind will definitely stimulate many researches in the recently emerging field of solar-driven water splitting.

Evaluation of a New Biosensor Based on in Situ Synthesized PPy-Ag-PVP Nanohybrid for Selective Detection of Dopamine.

In the present work, in situ synthesis of polypyrrole-silver-polyvinylpyrrolidone (PPy-Ag-PVP) nanohybrid using AgNO3 as an oxidant and polyvinylpyrrolidone (PVP) as a stabilizer and surfactant is demonstrated. The obtained ternary PPy-Ag-PVP nanohybrid was characterized by UV-vis, FT-IR, XRD, Raman, TGA, SEM, and HR-TEM analysis. Further the synthesized PPy-Ag-PVP has been investigated for its selective and sensitive sensing of dopamine (DA). The PPy-Ag-PVP modified glassy carbon electrode shows a reversible electrochemical behavior with superior response for DA. The limit of detection and limit of quantification are found to be 0.0126 and 0.042 µM (S/N = 3 and 10), respectively, with remarkable sensitivity (7.26 µA mM-1 cm-2). The practical application of the present modified electrode has been validated by determining the concentration of DA in human urine samples of different age group.