Fe-doped Samples Research Articles

Preparation and thermoelectric performance of tetrahedrite-like cubic Cu3SbS3 compound

Thermoelectric (TE) Cu3SbS3, as one of the Cu–Sb–S families, has the characteristic of strong anharmonicity of lattice vibrations. It may be a potential replacement for the unstable pristine tetrahedrite, provided that its cubic structure can be stabilised. In this study, pristine (near)-phase-pure cubic Cu3SbS3 and Fe-doped samples were successfully prepared by sequential use of equilibrium and non-equilibrium synthesis techniques. TE properties of both pristine and doped samples were optimised by tuning the sintering parameters. A maximum zT of 0.57 was achieved at 350 °C in pristine (near)-phase-pure cubic Cu3SbS3 sample hot pressed at 575 °C for 30 min, which is about 2.7 times higher than that of the spark plasma sintered one. The Fe-doped sample sintered at 575 °C for 45 min displays a higher zT in the whole testing temperature range and a maximum of 0.62 was reached at 350 °C. The influences of hot pressing and spark plasma sintering on the phase structure, microstructure, thermodynamic and TE properties were studied and correlated. The results demonstrated the potential of cubic Cu3SbS3 as a high-performance material.

Structure and optical properties of iron doped ZnSe microspheres

Iron (Fe) doped ZnSe microspheres were fabricated by solvothermal method. X-ray diffraction (XRD), Raman analysis, Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) results indicate that Fe2+ cations were incorporated into the zinc blende ZnSe lattices successfully and uniformly distributed in sample. SEM images displayed that doping with Fe2+ cations did not change the morphology of microspheres. The growth mechanism of Fe-doped ZnSe microspheres was proposed. The band gap increases and photoluminescence (PL) peaks in visible region show blue-shift as doping with Fe ions. In addition, a reduction in PL lifetimes in visible range was also observed, which may be due to the increase in non-radiative energy transfer between Fe2+ doping in the ZnSe matrix. The 5E↔5T2 transition of Fe2+ in the 3.6–5.5 μm spectral range was observed in Fe-doped sample at low temperature.

Effects of Fe doping on the visible light absorption and bandgap tuning of lead-free (CsSnCl3) and lead halide (CsPbCl3) perovskites for optoelectronic applications

The halide perovskite solar cells nowadays have emerged as a potential candidate for photovoltaic technology because of their high efficiency, low-cost, and facile fabrication process. In this study, the structural, elastic, electronic, and optical properties of pure and metal (Fe) doping lead-free perovskite CsSnCl3 and lead halide perovskite CsPbCl3 have been calculated by using density functional theory. The present study shows that the metal doping exhibits high absorption and high conductivity than the pure counterpart due to reducing the bandgap. The bandgap of Fe-doped CsSnCl3 is narrowing more than Fe-doped CsPbCl3. The Fe-doped CsSnCl3 reveals a more enhanced optical nature than the Fe-doped CsPbCl3 owing to the greater shipment of absorption peaks toward the lower energy region and the narrowing bandgap. The mechanical parameters show that the pure and Fe-doped samples are mechanically stable. The failure mode indicates that the Fe-doped perovskites are highly ductile in nature as pristine samples, which makes them suitable for use in thin films. The electronic band structure of doped samples exhibited the intermediate state (donor level) in the bandgap. The creation of intermediate states helps the excited photoelectron to easily transfer from the valence to the conduction band. A combined analysis of metal doping in lead halide and lead-free halide demonstrated that Fe-doped CsSnCl3 is more promising to use in solar cells and other optoelectronic applications.

Modification of magnetic properties, energy band gap and conduction mechanism of lanthanum orthochromite via (Sm, Fe) codoping

We report our investigations on the magnetic, thermal, optical and dielectric properties of the nanocrystalline La0.7Sm0.3Cr1−xFexO3 (0 ≤ x ≤ 0.3) samples synthesized through sol–gel auto-combustion process. The maximum magnetization and coercive field increase in Fe-doped samples. Fourier transform infrared (FTIR) spectra reveal the metal–oxygen (Cr/Fe–O) stretching and bending modes of vibration. Thermal analysis illustrates the occurrence of structural phase transition at ~ 290 °C for the pristine sample, and the phase transition temperature rises with the increase in Fe concentration. The specific heat capacity at constant pressure also reflects this transition. The energy band gap reduces for the doped samples. Dielectric constant, dielectric loss and loss tangent exhibit the usual frequency dependence and decrease with the amount of Fe. The Giuntini law implies higher contribution of polaronic conduction in the doped samples. Electric modulus analysis also shows the manifestation of both short- and long-range-order conduction processes in this system. The Nyquist plots for both impedance and electric modulus emphasize that grains dominate the conduction process. Temperature-dependent impedance and electric modulus analysis established that the relaxation processes are thermally activated and deviate from the ideal Debye behaviour.

Structure, optical and electronic characteristics of iron-doped cadmium sulfide under nonambient atmosphere

Iron-doped nano CdS was prepared in air and underflow of nitrogen applying the thermolysis technique. The impact of air and nitrogen atmosphere on the crystallinity and the different structure parameters of the obtained samples was investigated using X-ray diffraction measurements and applying Rietveld method. Analysis revealed the presence of two phases for CdS; hexagonal wurtzite and cubic zincblende with phase percentages greatly affected with preparation conditions; sample obtained under N2 is almost pure hexagonal (97%). The particle morphology was investigated by FE-SEM, and the associated EDS spectra manifested elements percentages in accordance with those intended for preparation. The optical bandgap was greatly affected; compared with samples formed in air, it reduced upon doping with Fe as well as upon preparation under N2, it decreased from 2.58 eV for pristine CdS to 1.99 eV for Fe-doped CdS under N2. The photoluminescence (PL) intensity was also affected by the condition of preparation and iron doping. Pure and Fe-doped CdS samples emitted violet and blue colors. Density function theory (DFT) calculations were performed to explain the reason for the reduction of the optical bandgap upon doping CdS with Fe. The comparison between different electronic characteristics of pure and Fe-doped CdS samples was explored also by DFT calculation.

An Innovative Model for Electronic Band Structure Analysis of Doped and Un-Doped ZnO

An empirical pseudopotential method, in conjunction with virtual crystal approximation and the compositional disorder effect, is exploited to extract the full electronic band structure of various ZnO thin films to ensure excellent agreement with the experimental results, and to compare with the theoretical results obtained on the basis of various density functional theories. The lattice parameters obtained through x-ray diffraction (XRD) studies have been used to characterize the full electronic band structure of various ZnO thin films. The whole work reported here has been carried out using the TNL FullBandTM simulator (Tech Next Lab). The impact of intrinsic and extrinsic doping and the formation of polycrystalline planes in thin film samples on the band gap parameter have been analyzed in terms of the internal structure factor, u. The rigorous analysis of crystalline and polycrystalline samples show that the band gap value is strongly dependent on the internal structure parameter, u. The u value has been found to be significantly affected by lattice disorder generated by the formation of various defects and polycrystalline planes in the thin films. An innovative model demonstrating the relationship between the alloy disorder effect and the internal parameter is reported. With the help of an innovative model, the value of alloy disorder parameters, P, have been extracted for undoped and 1, 2, and 3 at% Cd-, Sr-, and Fe-doped ZnO thin film samples, respectively. Reasonable agreement has been obtained between the reported and experimental optical band gap results. The results reported in the current article show superiority against previously theoretical results based on first-principles methods.

In situ and tunable structuring of semiconductor-in-glass transparent composite.

SummarySemiconductor-in-glass composites are an exciting class of photonic materials for various fundamental applications. The significant challenge is the scalable elaboration of composite with the desirable combination of tunable structure, high semiconductor loading ratio, and excellent transparency. Here we report that the topological engineering strategy via hybridization of the glass network former enables to surmount the aforementioned challenge. It not only facilitates the in situ precipitation of (Ga2-xAlx)O3 domains with continuously tunable composition but also allows to simultaneously refine the grain size and enhance the crystallinity. In addition, the composites exhibit excellent transparency and can host various active dopants. We demonstrate the attractive broadband optical response of the composite and achieve the pulse laser operation in mid-infrared waveband. The findings are expected to provide a fundamental principle of in situ modification in hybrid system for generation of high-performance semiconductor-in-glass composites.

Interplay between ferromagnetism and photocatalytic activity generated by Fe3+ ions in iron doped ZnO nanoparticles grown on MWCNTs

In order to limit the photogenerated charges recombination and to ensure an efficient photocatalytic degradation of RhB pollutant, a MWCNT-ZnO:Fe composite material was designed. Fe doped ZnO Nps grouped into quasi-spherical structures of about 100–250 nm were grown in situ on MWCNTs using sol-gel method. The XPS and UPS analysis allowed the identification of both Fe2+ and Fe3+ ionic species at substitutional and surface positions. The substitutional Fe3+ will generate an inverse Burstein-Moss effect and, as a result, the Fermi level is will be pushed down towards the valence band by 0.7, 0.45 and 0.29 eV for 2, 3 and 5% Fe doping respectively. The Fe doped samples show ferromagnetic behavior as determined from both ESR and magnetization measurements. The ferromagnetic order, the inverse Burstein-Moss effect, and the hole capture into the MWCNT valence band favors the charge separation of photogenerated e-h pairs and the reactive oxygen species (ROS) generation in ZnO. The proposed energy bands setup allowed to elucidate both ferromagnetic order formation and the photodegradation mechanism. Thus, an Fe doping degree of 5% ensured, besides the highest magnetization, a 97% photodegradation efficiency and a pollutant mineralization degree of 92%.

Influence of Cr and Fe doping on the structure, magnetic and optical properties of nano CuCo2O4

Nano CuCo2-xMxO4 (x = 0, 0.1, 0.2, M = Cr or Fe) samples were synthesized by hydrothermal method. Synchrotron x-ray diffraction data obtained for the samples were subjected to phase analysis and manifested a single-phase cubic spinel structure for Cr-doped samples, while for Fe-doped samples two phases were identified. Cation distribution and cell parameter (a) were obtained from Rietveld X-ray diffraction analysis. FTIR analysis affirmed the formation of the cubic spinel and the cation distribution obtained. The nano nature of the samples and the particle morphology were examined by high-resolution transmission electron microscope (HRTEM) with selected area electron diffraction (SAED). UV-diffuse reflectance revealed that all samples have two optical energy gaps. For all Fe doped samples, the optical band gaps decreased, while for Cr-content x = 0.1 the bandgaps increased then reduced for x = 0.2. Doped samples exhibited a blue or red shift depending on the kind and amount of the dopant ions. The PL intensity and the emitted colors depended on the kind and amount of the dopant ions. Magnetic measurements disclosed the paramagnetic nature of CuCo2O4, while a weak ferromagnetic is revealed for CuCo2-xCrxO4 and a ferromagnetic nature for CuCo2-xFexO4. Lowering the bandgap upon doping could make better mobility of lattice oxygen and enhancing the catalyst reducibility. Thus, the Cr and Fe-doped samples are expected to have better catalytic activity than the pristine one.

Thermal expansion and electrical properties of Fe-doped CaCu3Ti4O12 ceramics

Thermal behavior and electrical properties of Fe-doped CaCu3Ti4O12 ceramics samples have been studied by high-temperature X-ray diffraction, thermal analysis, and impedance spectroscopy. According to X-ray diffraction data, samples of CaCu3Ti4-4хFe4хO12-δ and CaCu3-3хFe3хTi4O12+δ composition do not contain iron-containing impurity phases; in trace amounts may contain copper oxide (II). According to thermogravimetry data, no weight loss of samples was recorded before the melting start temperature (~1033 °C). The DSC curves of doped calcium-copper titanate samples show an exothermic effect in the range of 506–573 K, not associated with a phase transition, and an endothermic process, at a temperature above 1219 K, due to the dissociation of CuO. The thermal expansion coefficient for CaCu3Ti3,76Fe0.24O12-δ in the range of 298–1193 K changes continuously from 8.6 × 106 (298 К) to 11.4 × 106 °С−1 (1173 К). Based on the results of impedance spectroscopy, the electrical properties of the samples were simulated and an equivalent scheme was proposed. The samples exhibit ionic conductivity. The activation energy of conduction of the CaCu3Ti3.76Fe0.24O12-δ is 0.65 eV and 1.04 eV of the CaCu3-3хFe3хTi4O12+δ.

57Fe Mössbauer spectroscopic study on the Fe doped supercapacitor birnessite, $$ ({\text{Na}},{\text{K}})_{x} {\text{Mn}}^{4 + }_{2 - x} {\text{Mn}}^{3 + }_{x} {\text{O}}_{4} \cdot 1.5{\text{H}}_{2} {\text{O}} $$

In the present work, the oxidation and spin state of Fe and the local structure around Fe in the supercapacitor birnessite with different contents of the Fe dopant were investigated using Mossbauer spectroscopy. It was found that Fe ions were exclusively present as high spin Fe3+ in octahedral coordination with about 70% iron occupying the Mn3+ positions and about 30% iron occupying the Mn4+ positions in the [MnO6] octahedra for all Fe-doped birnessite samples. Based on these new findings, the trend of typical cell parameters, selected bond lengths of the Fe-doped birnessites and their corresponding quadrupole splittings in the Mossbauer spectra were well explained by considering both the weakened Jahn–Teller effect during the replacement of Mn3+ by Fe3+ and the expansion of octahedra during the replacement of Mn4+ by Fe3+. The present work offers some new insights into the understanding of the mechanism of the heterogeneous atomic doping on the crystal structure of birnessite, with importance for both mineralogy and material science.

Crystal structures and proton transport properties of Sr2(Ti1-xMx)O4-δ (M = Fe, Al)

This study focuses on the effects of acceptor dopants in proton-conductive Sr2TiO4-based layered perovskites. We synthesized Sr2Ti0.9Fe0.1O4-δ (STF10) and Sr2Ti0.95Al0.05O4-δ (STA05) and evaluated the influence of ion substitution on their crystal structures, electrical conductivities, and proton transport properties. Our obtained results suggest that a redox reaction is the more favorable mechanism for the introduction of proton defects to Fe-doped samples compared with water vapor absorption, while the reverse is true for Al-doped samples. STF10 was found to exhibit a larger electrical conductivity at low temperatures than STA05. In addition, STF10 presented a proton transport number of 0.5 at 600 °C, while the corresponding value for STA05 was 0.5–0.6 at 450–600 °C. The higher proton transport number of STA05 at 450–550 °C compared to that of STF10 indicates that the Al-dopant suppressed the electronic conductivity owing to its constant valency. We therefore considered that characterization of the changes in material properties related to ion substitution can serve as a guide for material selection when developing proton-conducting solid oxide fuel cell technologies.

Photoluminescence properties of pure, Fe-doped and surfactant-assisted Fe-doped tin-oxide nanoparticles

A co-precipitation method with water as a distinctive solvent was used for the synthesis of pure, Fe-doped and surfactant-assisted Fe-doped SnO2 nanoparticles (NPs). Furthermore, the NPs were characterized using X-ray diffraction (XRD), Fourier-transform infrared, scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), UV–visible, photoluminescence spectroscopy and spectrofluorometer. XRD patterns showed a tetragonal rutile structure of SnO2 phase without additional peaks and a shift was noted for Fe-doped and surfactant-assisted Fe-doped samples. The crystallite sizes of Fe-doped and surfactant-assisted Fe-doped SnO2 NPs were found to decrease from 10.39 to 6.347 nm. Spherical morphology with uniform size was observed in all samples from SEM and HRTEM images. The presence of Sn, O and Fe ions was confirmed by EDAX analysis. The band gap energy of NPs was measured to be 3.487, 3.741, 3.845, 3.783 and 3.552 eV for pure, Fe-doped, cetyltrimethylammonium bromide, sodium dodecyl sulphate and Triton (surfactants) assisted Fe-doped NPs, respectively. An increase in the band gap was observed due to addition of Fe and surfactants. The photocatalytic study confirms that pure SnO2 NPs exhibit a significant photo-degradation of methylene blue dye under sun light. Moreover, the physical properties of SnO2 were modified by Fe-doping and addition of surfactants in comparison with pure SnO2 NPs.

Carrier recombination processes in Fe-doped GaN studied by optical pump–probe techniques

We applied time-resolved free carrier absorption and light-induced transient grating techniques for monitoring carrier dynamics in lightly Fe-doped GaN bulk crystals. Comparison of measured decay times at single- and two-photon carrier photoexcitation with those reported for higher Fe doping revealed two different branches of lifetime dependence on iron density. A deeper insight was reached by using different wavelengths for probing carrier dynamics, which enabled discrimination of electron and hole capture processes by Fe ions. The capture cross section for holes, σh = (4 ± 1) × 10−15 cm2 for the Fe2+* state (5E → 4T2 transition) was determined to be ten times larger than that for electrons, σe = (4 ± 1) × 10−16 cm2 for the Fe3+* state (4T1 → 3T1 transition). Thermal activation of the [Fe2+(5T2),hVB] complex, where hVB is a free hole, required an energy of 315 meV. Light-induced transient grating decay revealed decreasing diffusivity of electrons with Fe doping due to initial carrier capture to Fe3+ states. Simultaneous measurements of carrier diffusion coefficient and lifetime at low excitation conditions (3 × 1017 cm−3) revealed a decrease of bipolar diffusion length from 2 μm in the undoped GaN down to 0.08 μm in the Fe-doped samples at 300 K.

Effect of doping concentration for the properties of Fe doped TiO2 thin films applications

This paper reports the sol–gel preparation and subsequent characterization of Fe doped TiO2 thin films with different doping concentrations (1%, 3% and 5%). X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray analysis (EDX), UV–Visible analysis and Photoluminescence spectra analysis (PL) were used to characterize the prepared samples. The crystallite size of anatase phase increases from 4.76 nm to 7.61 nm when doping concentration increases from 1% to 3% and the anatase phase is transformed to brookite at the doping of 5% as the crystallite size of more than 14.82 nm. The surface morphological pictures are observing to be almost smooth and particle size dispensation of Fe doped titanium dioxide particles is non-spherical agglomeration crystallite formation. An optical band gap of 3.63 eV, 3.41 eV and 3.11 eV were obtained for the TiO2 thin films doped with 1%, 3% and 5% Fe respectively. PL analysis results the emission peaks at 347 nm for 1% Fe doped sample seems to shift slightly towards higher wavelength for 3% and 5% Fe doped samples. This may be due to reduction in bandgap because of the shallow trap state created near the absorption band edge as a result of doping.

Enhanced photocatalytic activity of Fe-doped Bi4O5Br2 nanosheets decorated with Au nanoparticles for pollutants removal

The two key factors such as light adsorption and separation of charge carriers in photocatalysts play crucial roles in determining the overall photocatalytic efficiency. Herein, we report synergetic effects of Fe-doping and Au nanoparticles (Au-NPs) deposition on the photocatalytic activity of the modified Bi4O5Br2 (BOB) nanosheets photocatalyst for Bisphenol A degradation and gaseous NO oxidative removal. Fe-doped BOB nanosheets decorated with Au-NPs are synthesized by a two-step chemical method. It was found that the Fe-doped BOB sample decorated with Au-NPs (Au-Fe-BOB) exhibits higher photocatalytic activity than the BOB, Fe-doped BOB, and Au-NPs-loaded BOB samples. Internal Fe-doping in the BOB enhanced the visible light absorption and the separation efficiency of photogenerated charge carriers acting as a scavenger. Moreover, the decorated Au-NPs in the composite photocatalyst extended the light adsorption in the range of visible and near- infrared light due to surface plasmon resonance effect of Au-NPs. The spin trapping measurements of Au-Fe-BOB composite photocatalyst show that the •O2− is a main reactive species during the photocatalytic reaction under visible-light irradiation. The excellent photocatalytic efficiency and stability of Au-Fe-BOB with visible-light response allow to be readily constructed and applied for practical removal of various pollutants using solar light in the future.

Evaluation of electronic transport and optical response of two-dimensional Fe-doped TiO2 thin films for photodetector applications

We have carried out the structural, electronic and optical properties of Iron (Fe)-doped TiO2 thin films by sol-gel technique. The results reveal that the thin films form in a granular structure where particle-like grains cover the surface. Photophysical features of the thin films are performed by UV–vis spectrometry. The optical bandgap of undoped TiO2 thin film decreases from 3.17 eV to 3.05 eV with an increase in atomic ratios of Fe content, so the electron transfer is easier from the valence band to the conduction band. The current-voltage (I–V) and capacitance-voltage (C–V) characteristics of the undoped and Fe-doped TiO2 thin films are investigated under dark and various lighting intensities. Our results show that the photocurrents increase with increasing intensities of illumination. The photodiodes also show a decreasing capacitance with increasing frequency. From I–V and C–V plots, the photodiodes show rectifying properties and good photovoltaic behavior. Herein, the results display that the produced new Fe-doped TiO2 thin film samples can be used for photodetector applications.

Fe-Doped Mesoporous Alumina: Facile One-Pot Synthesis, Modified Surface-Acidity and Its Enhanced Catalytic Performance in Phenol Hydroxylation

Fe-doped mesoporous alumina (MA) was successfully synthesized via a facile one-pot synthesis method. The resulting Fe-doped MA samples possess typical mesoporous structure, relatively high BET surface area, and narrowed pore size diameter. Besides, the iron species are well-dispersed in the alumina matrix, and more importantly, some small oligonuclear iron oxide clusters are linked on the surface of alumina, leading to the elimination of strong acid sites. The reaction of phenol hydroxylation was preceded at room temperature for 2 h. The introduction of mesoporous structure in alumina would be favorable for the adsorption and diffusion process of reactant and product molecules, and also the well-dispersed iron species in alumina matrix and large amount of acid sites stimulate more active hydroxyl radicals which are greatly beneficial for the catalytic process, especially the elimination of strong acid sites would inhibit the over-oxidation reaction. In this case, the sample of 5Fe–MA displays the best catalytic performance especially with the extremely high dihydroxybenzene selectivity of 93.2%, and the good catalytic stability is also evidenced by the five times recycling tests. In this work, the Fe-doped mesoporous alumina (MA) was successfully prepared. The iron species are well-dispersed in the alumina matrix, and some small oligonuclear iron oxide clusters are linked on the surface of alumina, leading to the elimination of strong acid sites. The advanced properties of mesoporous structure, well-dispersed metal active centers and lack of strong acid sites in Fe-doped MA are greatly beneficial for the catalytic process, especially for the dihydroxybenzene selectivity with extremely high value of 93.2%.

Efficient photocatalytic CO2 reduction by visible-light responsive Fe-doped WO3 nanostructures

The nanoparticles of WO3 doped with Fe ions have been employed for University, Kermanshah photocatalytic conversion of greenhouse gaseous of CO2 and CH4 under visible-light irradiation. The photocatalysts have been characterized by XRD, FESEM, EDX, Raman, UV-vis, and PL techniques. The XRD and Raman spectroscopies confirm the monoclinic structure of WO3 nanoparticles and also the successful incorporation of Fe ions into WO3 lattice. A red shift in Raman patterns of Fe-doped WO3 samples indicate the partial substitution of W with Fe ions and the structural defects induced in WO3 crystals upon doping treatment. The recorded PL signals reveal that the charge carrier recombination rate can be inhibited by doping WO3 with Fe ions. The modified samples show high activity by photons with wavelength equal to/greater than ~500 nm, the visible-light in green region. The best photocatalytic reduction of CO2 is provided to be 38.7% by WO3 containing 4.18 at.% Fe under visible-light. Ethane, and formate and acetate derivatives are detected as the major products of CO2 reduction.

Crystal Chemistry, Band-Gap Red Shift, and Electrocatalytic Activity of Iron-Doped Gallium Oxide Ceramics.

This work for the first time unfurls the fundamental mechanisms and sets the stage for an approach to derive electrocatalytic activity, which is otherwise not possible, in a traditionally known wide band-gap oxide material. Specifically, we report on the tunable optical properties, in terms of wide spectral selectivity and red-shifted band gap, and electrocatalytic behavior of iron (Fe)-doped gallium oxide (β-Ga2O3) model system. X-ray diffraction (XRD) studies of sintered Ga2–xFexO3 (GFO) (0.0 ≤ x ≤ 0.3) compounds provide evidence for the Fe3+ substitution at Ga3+ site without any secondary phase formation. Rietveld refinement of XRD patterns reveals that the GFO compounds crystallize in monoclinic crystal symmetry with a C2/m space group. The electronic structure of the GFO compounds probed using X-ray photoelectron spectroscopy data reveals that at lower concentrations, Fe exhibits mixed chemical valence states (Fe3+, Fe2+), whereas single chemical valence state (Fe3+) is evident for higher Fe content (x = 0.20–0.30). The optical absorption spectra reveal a significant red shift in the optical band gap with Fe doping. The origin of the significant red shift even at low concentrations of Fe (x = 0.05) is attributed to the strong sp–d exchange interaction originated from the 3d5 electrons of Fe3+. The optical absorption edge observed at ≈450 nm with lower intensity is the characteristic of Fe-doped compounds associated with Fe3+–Fe3+ double-excitation process. Coupled with an optical band-gap red shift, electrocatalytic studies of GFO compounds reveal that, interestingly, Fe-doped Ga2O3 compound exhibits electrocatalytic activity in contrast to intrinsic Ga2O3. Fe-doped samples (GFO) demonstrated appreciable electrocatalytic activity toward the generation of H2 through electrocatalytic water splitting. An onset potential and Tafel slope of GFO compounds include ∼900 mV, ∼210 mV dec–1 (x = 0.15) and ∼1036 mV, ∼290 mV dec–1 (x = 0.30), respectively. The electrocatalytic activity of Fe-doped Ga-oxide compounds is attributed to the cumulative effect of different mechanisms such as doping resulting in new catalytic centers, enhanced conductivity, and electron mobility. Hence, in this report, for the first time, we explored a new pathway; the electrocatalytic behavior of Fe-doped Ga2O3 resulted due to Fe chemical states and red shift in the optical band gap. The implications derived from this work may be applicable to a large class of compounds, and further options may be available to design functional materials for electrocatalytic energy production.