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In this study, we presented hollow bimetallic mixed oxides of molybdenum and nickel, prepared through a facile polymer-assisted solution process. Our focus was on addressing the influence of polymer concentration on the formation of hollow nanoparticles (HNPs) of the bimetallic mixed oxides, a critical aspect explored through XRD, Raman, and TEM analyses. Raman study indicated that as the PAA concentration increases, the oxygen vacancies become more dominant with a decrease in the O/Mo ratio. The formation process of the hollow structure in the MoO3/NiMoO4 nanostructure was confirmed using FESEM and TEM. The influence of oxygen vacancies over the surface of the mixed oxides and their concentration was examined by XPS analysis. The resulting MoO3/NiMoO4 HNPs serve as catalysts for the oxygen evolution reaction (OER), and their performance was systematically investigated using ECSA, EIS, CV, and LSV analyses. The superior electrochemical performance of the optimized mixed oxide composite is attributed to the increased number of oxygen vacancies, electrical conductivity, and a reduced Tafel slope. Notably, the best composite exhibits a 3-fold increase in electrochemical surface area and a lower overpotential. Specifically, the reduction in the Tafel slope from 142.2 to 97.5 mV dec−1 and the overpotential from 402 to 330 mV for HNPs prepared with PAA 0.10 g/10 mL and PAA 0.15 g/10 mL, respectively, underscores the efficacy of the developed catalyst. DFT calculations of the OER were found to be uphill in energy which makes the *O to *OOH step the PDS for defective metal oxide with a ΔG of 3.00 eV. This research contributes valuable insights that open new avenues for the application of molybdenum oxides and their derivatives in water-splitting processes. The findings not only address the challenges in OER kinetics but also hold promise for advancing the field of green hydrogen production through enhanced electrocatalytic materials. [ABSTRACT FROM AUTHOR]

A new class of 2D Ti3C2Tx (MXene) in different weight percentages (0, 1, and 2 wt.%) are hybrid with TiO2 nanopowder to form TiO2/MXene nanohybrids by artist spray gun assisted (ASG) pyrolysis method to use an electron transport layer (ETL) for carbon perovskite solar cell (PSC). The influence of Ti3C2Tx on TiO2 in light absorption, charge separation and carrier dynamics is studied in detail. The formation of TiO2/MXene is studied by X‐ray diffraction analysis. The emission spectrum, charge separation and carrier dynamics of TiO2/MXene nanohybrid are analyzed by photoluminescence studies. They exhibit an emission spectrum at 390 nm. The photoluminescence and electrochemical impedance results reveal that the Ti3C2Tx nanosheets provide a superior charge transfer path with less electron transfer resistance at the ETL/perovskite interface, which lead to produce higher photocurrent. This study reveals that TiO2/MXene nanohybrid can be used as a promising ETL to enhance the photo‐conversion efficiency of carbon PSC. These results reveal that TiO2‐ MXene (1 wt.%) nanohybrid ETL shows the highest PCE of 5.15% than that of TiO2‐ MXene (2 wt.%) nanohybrid ETL and pristine TiO2 ETL‐based PSC (4.64%). [ABSTRACT FROM AUTHOR]

The synthesis of active thin films supported on substrates overcomes the drawbacks of powder-based photocatalysis and energy harvesting. In this study, semiconducting thin films of pristine TiO2 and Sn doped TiO2 were coated on glass substrates by the sol–gel dip-coating method. The effect of both annealing temperature (450 and 500 °C, during 2 h in air atmosphere) and Sn dopant content (1, 3 and 5 at.%) on the structural, morphological and optical properties of Sn doped TiO2 films were studied. The correlation between these properties and the photocatalytic performance of the films in the removal of Rhodamine B solution under UV light was investigated. At 450 °C, Sn:TiO2 films exhibit anatase–brookite mixed phase, while at 500 °C, the films exhibit anatase phase. The crystallites sizes of the films were on a nanometer scale, between 19.01 and 26.57 nm. The pristine TiO2 film treated at 450 °C has a compact morphology with spherical grains, and after adding different Sn content, the nano-spheres turn into nanorods. At 500 °C, all the films illustrate a porous morphology with spherical grains. The two series are transparent in the visible region and have an optical band gap of 3.23–3.54 eV. The (e−/h+) recombination rate of TiO2 film decreases as a function of Sn doping. The latter enhances the photocatalytic efficiency of porous TiO2 film and 1 at.% Sn:TiO2 exhibits the highest degradation rate, which can be attributed to a larger surface area and less (e−/h+) recombination rate. [ABSTRACT FROM AUTHOR]

Summary: Cu2AgInS2Se2 alloyed quantum dots are synthesized through a simple hot injection method. Its tetragonal structure and crystallite size are determined by using X‐ray diffraction analysis. Its optical properties are observed by using Ultraviolet‐Vis absorption and PL emission spectroscopies. The oxidation state and elemental composition of Cu2AgInS2Se2 quantum dots are confirmed by X‐ray photoelectron spectroscope analysis and energy dispersive X‐ray analysis, respectively. The optical bandgap of the synthesized quantum dots is measured to be 1.29 eV. The synthesized Cu2AgInS2Se2 quantum dots are sensitized onto the porous TiO2 nanofibers (CAISSe/P‐TiO2) and its morphological and optical properties are examined. The quantum dot sensitized solar cell is assembled using CAISSe/P‐TiO2, polysulfide and Cu2S as the photoanode, electrolyte and the counter electrode exhibited photoconversion efficiency (PCE) of 5.87%, which is significantly higher than that assembled using Cu2AgInSe4 (4.21%) and Cu2AgInS4 (4.89%) quantum dots sensitized porous TiO2 NFs as the photoanodes. [ABSTRACT FROM AUTHOR]

In this work, quaternary Cu2AgInS4 (CAIS) and Cu2AgInSe4 (CAISe) nanoparticles (NPs) were synthesised by a simple hot injection method and were confirmed by XRD and Raman spectroscopy analysis. The morphologies of the synthesised CAIS and CAISe nanoparticles were confirmed by HR-TEM. The synthesised CAIS and CAISe NPs were deposited over pearl carbon (C) coated FTO and this was confirmed by Raman spectroscopy analysis. The photoluminescence (PL) spectra of the perovskite deposited onto CAIS NPs@C and CAISe NPs@C films were recorded to determine their charge extracting behaviour. The PL intensity was quenched on the CAIS NPs@C film and this is consistent with its photovoltaic performance. Among these two hole transporting material, the distribution of CAIS NPs onto a pearl carbon based counter electrode (CE) enhanced the charge transport and charge collection efficiency and reduced the recombination loss more than the CAISe NPs deposited onto a pearl carbon based CE. The synergistic effect of pearl carbon and CAIS NPs reduced the leakage current and increased the charge transport at the pearl carbon/perovskite interface. This enhanced the device performance, which exhibited a maximum PCE of 4.24% with ∼57% improvement over the pearl carbon CE. [ABSTRACT FROM AUTHOR]

In the present study, quaternary Cu2AgInS4 quantum dots (CAIS QDs) are synthesized by a hot injection method. The crystallographic information of the QDs is confirmed by X-ray diffraction and high-resolution transmission electron microscopy studies. Energy dispersive X-ray spectrum analysis reveals a 1.93 : 1.0 : 1.01 : 3.80 elemental composition ratio of the synthesized QDs. X-ray photoelectron spectroscopy analysis confirms the oxidation states of the elements present in the synthesized QDs. The optical properties are studied using UV-VIS absorption spectroscopy and PL emission spectroscopy. From a Tauc plot, the bandgap of the synthesized QDs is calculated to be 1.6 eV. The synthesized QDs are used as sensitizers and are loaded onto P-TiO2 NFs using 3-mercaptopropionic acid as a bifunctional linker as well as without the use of a bifunctional linker. Quantum dot sensitized solar cells (QDSCs) are fabricated using Cu2AgInS4 QD sensitized porous TiO2 NFs as the photoanode, Cu2S as the counter electrode and polysulphide as the electrolyte, in order to study its photovoltaic performance. These results revealed that the QDs loaded onto the porous TiO2 NFs using a bifunctional linker exhibits 27% improvement in the photoconversion efficiency of QDSC than that of the QDs loaded onto the porous TiO2 NFs without the use of a bifunctional linker. [ABSTRACT FROM AUTHOR]