Proton battery (PB) technology has regained attention in recent years as a promising energy storage alternative to conventional lithium-ion batteries due to its excellent electrochemical performance, scalability, and environmental friendliness. To assess its potential, we provide a comprehensive review of its re-emergence, including its historical background, construction, working principles, and favorable materials. The growing global demand for energy storage and the role of PBs in addressing this need are highlighted, and the historical background tracing the evolution of PBs, from their early conceptualizations to recent advancements, is covered. Battery components such as electrodes and electrolytes are discussed, and the mechanisms underlying proton conduction, catalytic activity, and surface chemistry at the electrode-electrolyte interfaces are also summarized. Furthermore, various proton-conducting materials and media are examined, along with a discussion on their structural and electrochemical properties. Finally, a SWOT analysis covers the strengths, weaknesses, opportunities, and threats of PBs and offers valuable perspectives regarding R&D prospects. This review emphasizes the need for continued innovation to unlock the full potential of PBs as sustainable energy storage alternatives.

Density functional theory calculations were performed using the Tran-Blaha modified Becke-Johnson exchange–correlation functional, to study the structural, electronic, optical, and thermoelectric properties of Ca-substituted SrO. For comparative simulation and experimental investigations, Ca-substituted SrO thin films were grown using a chemically derived technique. X-ray diffraction analysis revealed prominent diffraction peaks indexed as the (111) and (200) planes of the cubic phase of SrO. Surface analysis demonstrated the trend of increasing porosity and decreasing grain size at higher calcium substitution levels. The evaluated density of states of SrO are primarily influenced by Sr-d and O-p orbitals, while the substitution of Ca introduced a hybridization of O-p, Sr-d, and Ca-d orbitals. The simulated optical band gap of SrO was observed as 5.02 eV which experienced a variation with Ca-substitution. The thermoelectric properties indicated enhanced electrical conductivity for Ca-substituted SrO compositions. The key findings of simulations and experiment are consistent, and the improved properties suggest these compositions suitable for thermoelectric and optoelectronic applications.

Strontium oxide and magnesium-doped compositions were analyzed using density functional theory to explore their electronic, thermoelectric, and optical properties. Magnesium-doped SrO thin films with various concentrations were experimentally prepared on silicon substrates using the sol-gel spin-coating technique. Structural analyses confirmed the stable single-phase cubic crystalline structure, unaffected by doping. Electronic studies revealed a reduced band gap and the formation of states near the Fermi level, improving charge carrier transport. The thermoelectric evaluation indicated enhanced electrical conductivity that observed for pure SrO as 4.42 x 1019 (Omega m s)-1, whereas 9.43 x 1019 (Omega m s)-1 for maximum Mg containing composition. The lowered thermal conductivity is contributing to superior thermoelectric performance. Optical analyses demonstrated improved absorption and reduced optical band gap, affirming enhanced light interaction capabilities. The highest refractive index and real epsilon values were recorded at the higher energy regimes approximately 2.94 and 12.89, respectively, for composition containing maximum dopant content. The optical band gap of SrO was calculated as 2.50 eV and found to decrease with increment of Mg substituting concentration. Experimental results showed strong alignment with theoretical predictions, underscoring the potential of Mg-doped SrO thin films as promising candidates for advanced optoelectronic and thermoelectric applications.

Photoelectrochemical (PEC) water splitting technique is one of the most promising, cost-effective, and environmentally friendly techniques for solar H2 production. However, the widely accepted TiO2 semiconductor photocatalyst for a PEC system portrays less visible light absorption due to its wide bandgap and rapid recombination of e-/h+ pairs that ultimately lead to its low hydrogen production efficiency. Herein this work, heterostructure graphene quantum dots (GQDs) and cupric oxide (CuO) modified TiO2 based photocatalyst were prepared to elucidate the optoelectronic and charge transfer properties of the TiO2 based photocatalysts to enhance their photocatalytic performances. The GQD and CuO modified TiO2 based photocatalysts were synthesized via hydrothermal synthesis technique at calcination temperature of 450 degrees C for calcination durations up to 3 h. The effect of the dopants was investigated on various physiochemical properties including structural, morphological, chemical, elemental, optoelectronic and as well as, photoelectrochemical properties. The developed CuO/GQD@TiO2 heterostructure photocatalyst presented the lowest energy bandgap (2.16 eV), enhanced visible light absorption (up to-745 nm), and reduced recombination of the charge carriers. The optimized tri-layered novel CuO/GQD@TiO2 photocatalyst demonstrated maximum H2 production up to 34,466 mu mol g-1h-1 with photoconversion efficiency-9.01 %. Overall, the presented mechanistic insight and targeted strategy of incorporating CuO and GQD into TiO2 photocatalyst provides a fresh perspective in producing H2 efficiently using PEC approach.

Zirconium dioxide is known for its outstanding mechanical, thermal, and optical properties, making it suitable for various applications. The main objective of this work was to investigate the effects of Pr doping on various properties of ZrO2, combining simulation and experimental methods. The simulations were carried out using density functional theory calculations, while thin films were fabricated through a chemically derived method for experimental analysis. The combination of these two methods allows for a comprehensive understanding that link theoretical predictions with experimental findings. The electronic properties revealed a reduction in the band gap upon doping which improves energy absorption. The thermoelectric properties showed enhanced performance, highlighting its potential for energy conversion applications. X-ray diffraction analysis confirmed the tetragonal phase. Optical investigations demonstrated notable changes in the absorption and refractive index with Pr doping. These findings provided a comprehensive understanding and highlighting its potential for advanced optoelectronic and thermoelectric applications.

This study examined the effects of Mg doping on the structural, optical, photoluminescence, and dielectric properties of a series of double perovskite Sr2-xMgxFeNbO6 (0.00 <= x <= 0.40) ceramics that is successfully manufactured by using the mixed oxide route. It was proven by X-ray diffraction that a single-phase monoclinic perovskite (space group P21/c.) had formed, and at increasing Mg concentrations, SEM showed reduced porosity and increased grain uniformity. Tauc analysis and UV-Vis spectroscopy revealed a consistent decrease of the bandgap from 2.77 eV to 2.46 eV, which was ascribed to defect-induced electronic states and lattice distortion. The presence of levels of recombination-active defects was further confirmed by photoluminescence spectra. At high temperatures (similar to 560 degrees C), dielectric studies revealed a low loss (tan delta = 2.0) and a high dielectric constant (epsilon(r) approximate to 800), which made these materials attractive options for wireless communication components. Mg-doped Sr2FeNbO6 ceramics have the potential for advanced applications in microwave electronics and optoelectronics due to their superior dielectric behavior, bandgap tunability, and integrated structural stability.

This study explores the effects of strontium doping on the electronic, structural, and optical properties of Cu2O thin films using a hybrid approach. Density functional theory was employed to support the experimental results. The DFT model optimized the calculation of the total density of states which further revealed that the valence band predominantly consists of Cu-d and O-p orbitals, whereas a major contribution to the conduction band was made by Sr-d states. The structural variations induced by Sr doping, like changes in crystallite size, peak intensity, and defect, were examined using X-ray diffraction analysis. Field emission scanning electron microscopy indicated significant changes in grain shape and size with increasing Sr content. Optical properties were analyzed to demonstrate the effect of Sr doping, by simulation and experimentally using spectroscopic ellipsometry. A considerable decrease in band gap was observed as 2.25 eV for un-doped and 1.69 eV for maximum Sr-doped composition. A combined analysis of both theoretical and experimental studies has shown how Sr doping changes Cu2O properties and makes it a reliable material for optoelectronic and photovoltaic applications.

The current study presents the influence of Ti doping on the electronic, structural, and optical properties of Cu2O. The investigation employs a comparative approach, integrating theoretical calculations using density functional theory and experimental outcomes. Density of states spectra depicted the maximum contribution of Cu-d and O-p in the valence band, whereas Ti-d states filled the conduction band. Structural changes induced by Ti doping, including variations in peak intensity, crystallite size, and defects were examined in detail by X-ray diffraction analysis. The field emission scanning electron microscopy described grain morphology significantly changing upon Ti doping. Optical properties were scrutinized to determine variations in optical parameters. For both un-doped and Ti-doped Cu2O, the experimentally measured band gap was found to be decreased, ranging from 2.05 eV to 1.69 eV. The comparative studies enable a valuable understanding of the effectiveness of Ti doping in modifying the properties of Cu2O.

To study the Mg-doped ZrO 2 , the electronic, thermoelectric, and optical properties were characterized by first principle as well as experimental techniques. For experimental observations, the samples for pure ZrO 2 and Mg-doped ZrO 2 thin films were prepared. A noticeable difference was observed between the results of electronic, thermoelectric, and optical properties of pure and Mg-doped ZrO 2 thin films. The electronic properties extracted from simulations show that Mg-doped ZrO 2 , Mg-s, Zr-d, and O-p states provide the main contributions. The electrical conductivity and Seebeck coefficient present an increasing trend with doping of Mg content. The absorption coefficient trend shows that the material becomes more absorbing with the increase in Mg content. The refractive index reduces from ∼2.2 to ∼1.8. The content of Mg carries corroborates the substantial variation in optical parameters with varying energy ranges. The comparison is carried out between the results of optical properties deduced through simulations and spectroscopic ellipsometry.

The properties of Nd-doped WO3 thin films are studied to assess their suitability for photovoltaic and optoelectronic applications. The simulations on pristine and Nd-doped WO3 were performed using Tran Blaha modified Becke-Johnson approximation to explore the various properties, whereas the spin coating technique was employed to synthesize thin films. X-ray diffraction analysis revealed the crystalline cubic structure in all synthesized thin films. The morphology contains uniform rod-like features and the width of these were enhanced in doped composition. The projected density of states demonstrated the major prominent contributions of W-d in conduction and O-p in the valence band while Nd-f orbital plays a major contribution in doped compositions. Thermoelectric parameters were found to change significantly with Nd incorporation in WO3. The highest refractive index and real epsilon values were recorded at the higher energy regimes approximately 2.96 and 8.61, respectively, for compositions containing maximum dopant content. The optical conductivity and absorption coefficient showed an enhanced trend in doped composition which is considered favourable for improved optoelectronic and photovoltaic applications. The experimental band gap of WO3 was calculated as 2.03 eV and found to decrease with increment of Nd doping concentration.

Investigation on different materials at the nanoscale has transformed the significant aspects of technology, especially the revolution in microelectronic and optoelectronic devices. In this context, the first principle and experimental investigations on Cr-doped Ta2O5 compositions are presented. The simulations for electronic, thermoelectric and optical properties were performed through DFT TB-mBJ calculations. The p-d hybridization between Ta and O atoms appeared in the density of states spectra. Experimentally, Cr-doped Ta2O5 thin films were fabricated through a well-known magnetron sputtering technique. The crystallographic studies reveal the growth of the orthorhombic structure of Ta2O5. The Cr in thin films leads to grain growth which increases with Cr dopant content. Thermoelectric properties especially the Seebeck coefficient of Cr-containing compositions are improved. The optical parameters are recorded as a function of photon energy which shows a resemblance in simulation and experimental results. The maximum value of the experimental refractive index for all compositions was noticed at the highest energy regimes and found to increase from 2.34 to 3.65 with maximum Cr content. Similarly, the maximum value of real epsilon enhanced from 3.59 to 12.01. The improved thermoelectric and optical properties make these compositions favorable for energy harvesting and photovoltaic applications.

Tantalum oxide and tantalum oxynitride structures were examined through density functional theory using the trans-blaha-modified Becke–Johnson approximation and an experimental approach for the prediction of electronic, thermoelectric, and optical properties. Pure Ta2O5 and Ta2O5-xNx thin films were prepared using the well-known DC magnetron sputtering for comparative computational and experimental investigations. The thermoelectric properties were evaluated, and a considerable improvement in parameters was observed with an increase in dopant concentration. Phase identification and structural analysis of the thin films were performed using x-ray diffraction analysis. The optical band gap measured by the Tauc relationship showed a decrease in the band gap from 2.57 to 2.05 eV with the increase in nitrogen content which followed the simulation trend. The experimental investigation of the optical parameters of pure and N-doped Ta2O5 thin films was carried out. The simulation and experimental results depicted an epsilon near-zero response with maximum N doping (Ta2O1.25N3.75) in the visible and near-infrared regimes. The theoretical and experimental results showed nearly identical correlations. These thin films are considered suitable potential candidates for thermoelectric and optoelectronic applications due to their unique enhanced parameters.