Zeeshan, Hafiz

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Interface engineering and Oxygen vacancy control in SrTiO₃-TiO₂ eutectics
(Wiley, 2026-01-01)
Hou, Zhiwei
;
Guo, Yefei
;
Zeeshan, Hafiz Muhammad
;
Voloshina, Elena
;
Dedkov, Yuriy
The development of highly efficient semiconducting materials is essential for achieving the high-yield and stable hydrogen and/or oxygen evolution reactions (HER/OER) in photoelectrochemical (PEC) water splitting reactions. The SrTiO3-TiO2 eutectic compound has recently emerged as a perspective material with extraordinary activities in the PEC field due to the unique crystallographic and electronic properties caused by the large number of oxygen vacancies in the bulk. In the present study, different experimental techniques (XPS, SEM/EDX, TEM/EDX) are used to provide a detailed investigation of the changes in the structural and electronic properties of the SrTiO3-TiO2 eutectic upon annealing under various gaseous environments (in vacuum, air, oxygen, argon). These results demonstrate that thermal annealing in different environments significantly enhances the formation of a sharp interface between the two crystalline phases and allows to control the concentration of the oxygen vacancies within the eutectic material.
Publicationtype: Journal Article
22 23
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Structure and electronic properties of SrTiO3–TiO2 eutectic for water splitting applications
(Wiley-VCH, 2023-11-01)
Guo, Yefei
;
Zeeshan, Hafiz Muhammad
;
Yan, Mouhui
;
Qin, Weimin
;
Yang, Wanting
Semiconductors with bandgaps and edges corresponding to the solar energy spectrum are found to be suitable for the water splitting applications using photoelectrochemical reactions. However, many present-day materials used in these applications do not have high stability and/or high effectiveness over the complete sunlight spectral range. The recently proposed eutectic compounds, which combine two or more semiconducting materials, can overcome many present difficulties and extend the light absorbance spectrum improving the effectiveness of the water splitting cells. Herein, structural and electronic properties studies of the SrTiO3–TiO2 eutectic material, which is a representative example of this family, are presented. It is found that structural properties of this material, particularly the phase separation and formation of the sharp interface between two phases, can be significantly improved up on the thermal annealing, which is very important for their application in the water splitting reactors. The findings present the deep understanding of the interface structure and electronic properties of the SrTiO3–TiO2 eutectic, which can help to improve the functionality of these class of materials in different applications.
Publicationtype: Journal Article
20
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Stability of van der Waals FePX₃ materials (X: S, Se) for water-splitting applications
(2023-01)
Sharma, Sandhya
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Zeeshan, Hafiz Muhammad
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Panahi, Mohammad
;
Jin, Yichen
;
Yan, Mouhui
The interaction of high-quality transition metal trichalcogenides (TMTs) single crystals FePX₃ (X: S, Se) with water molecules is studied using near-edge x-ray absorption fine structure (NEXAFS) and x-ray photoelectron spectroscopy (XPS) in a wide range of temperature and partial pressure of H₂O. The physisorption nature of interaction between H₂O and FePX₃ is found at low temperatures and relatively small concentrations of water molecules, that is supported by the DFT results. When temperature of the FePX₃ samples and partial pressure of H₂O are increased, the interaction at the interface is defined by two competing processes—adsorption of molecules at high partial pressure of H₂O and desorption of molecules due to the increased surface mobility and physisorption nature of interaction. Our intensive XPS/NEXAFS experiments accompanied by DFT calculations bring new understanding on the interaction of H₂O with surface of a new class of 2D materials, TMTs, pointing to their stability and reactivity, that is important for further applications in different areas, like sensing and catalysis.
Publicationtype: Journal Article
15
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Investigating the electrochemical properties of SnO monolayer in sodium-ion batteries
(Elsevier, 2022-12-01)
Butt, Mehwish Khalid
;
Rehman, Javed
;
Alofi, Ayman S.
;
Yang, Zhao
;
Zeeshan, Hafiz Muhammad
The increasing energy crises have driven the world toward the exploration of clean and renewable energy sources. The selection of electrodes is a fundamental step in sodium (Na)-ion batteries (SIBs) to achieve extraordinary performance. Two-dimensional (2D) materials are strong candidates as electrode materials for SIBs owing to their enormous surface area, high thermal and electrical conductivities, and plenty of accumulation sites for adsorption of Na atoms. In this study, we investigate the electrochemical performance of two-dimensional tin mono-oxide (SnO) monolayers as an anodic material for SIBs using first-principles calculations. The electronic band structure, adsorption process, diffusion mechanism, and storage capacity of Na atoms in the SnO monolayer are examined. Our simulations disclose the semiconducting nature of the SnO monolayer, which becomes metallic after adsorption of a minor amount of Na atoms. This metallic behavior provides good electrical conductivity and mobility with low diffusion energy (0.15 eV) for the migration of Na on the SnO monolayer, indicating a rapid charge–discharge process. Furthermore, the determined specific capacity of the Na-loaded SnO monolayer is 398 mAh g−1 with low average open circuit voltage of 0.60 V. The above encouraging results show that the SnO monolayer is a promising anode for rechargeable SIBs.
Publicationtype: Journal Article
28
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Semiconducting eutectic materials for photocatalysis and photoelectrochemistry applications : a perspective
(Royal Society of Chemistry (RSC), 2022-09-27)
Zeeshan, Hafiz Muhammad
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Sharma, Sandhya
;
Panahi, Mohammad
;
Voloshina, Elena
;
Dedkov, Yuriy
The world of semiconductors has drastically improved human lifestyle due to its versatile applications. The demand for new efficient semiconductors is increasing day by day, giving birth to the idea of new synthesis methods. Here, the importance of semiconductor eutectic materials has been presented, as one of the potential candidates for solar-based devices such as photo-anodes for water splitting, along with the micro (μ) pulling method (as a synthesis method for semiconductor eutectic materials). A comparison of the efficiency of the present devices with the eutectic composites has been made, showing semiconductor eutectic materials as a better alternative. In addition, possible changes that can be achieved using the μ-pulling method to enhance the photo(electro)chemical (PEC) properties have focused on semiconducting eutectic materials in this article.
Publicationtype: Review Article
4
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SnSe₂ monolayer is a promising Na host material : a DFT study
(Elsevier, 2021-12-01)
Butt, Mehwish Khalid
;
Dinh, Van An
;
Zeeshan, Hafiz Muhammad
;
Yang, Zhao
;
Wang, Shuanhu
Na ion batteries (SIBs) have attained tremendous consideration due to their environmental friendliness, natural abundance and low costs. In this study, the electronic and electrochemical characteristics of SnSe₂ monolayer for SIBs are investigated by using first principle calculations. The electronic structure of 2D SnSe₂ exhibit semiconducting character with band gap of 0.85 eV and 1.4 eV by using PBE-GGA and HSE06 schemes, respectively. Our computation revealed that Na adsorbed SnSe₂ system demonstrate metallic characteristics. With rise of Na loading, the electronic conductivity of the host materials upsurges. An average open circuit voltage (OCV) of 0.662 V is perceived with Na storage capacity of 387 mAhg−1. This capacity is greater than the commercial anode materials (i.e. graphite has storage capacity of 372 mAhg−1 and 273 mAhg−1 for LIBs and KIBs, respectively). Furthermore, a significantly low activation energy (104 meV) for Na diffusion on the SnSe₂ monolayer surface is obtained. Hence, these outcomes suggest that SnSe2 monolayer is a potential applicant for SIBs.
Publicationtype: Journal Article
7
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A unique photo charge behaviour of bare-KTaO3
(2021-10-15)
Zeeshan, Hafiz Muhammad
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Rafiq, Mubashar
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Butt, Mehwish Khalid
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Yang, Ruishu
;
Wang, Shuanhu
A deep understanding of UV light response of KTaO3 (KTO) has been explored by means of temperature dependent UV treatment. Two different temperature dependent measurement schemes have been utilized to differentiate between the shallow carriers and deep carriers. A fake transition at 220 K is found, which is actually due to the UV-induced oxygen sub-bands, resulting in the transition in photo-response from transient to persistent. Giant change in the resistance is observed for cooling as compared to heating of substrate, which is credited to the small recombination rate at low temperatures. This temperature dependent resistance response of KTaO3 under UV light provides an importance of the measurement way of photo-charge carriers in KTaO3.
Publicationtype: Journal Article
12
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Monolayer SnC as anode material for Na ion batteries
(Elsevier, 2021-09-01)
Khalid Butt, Mehwish
;
Zeeshan, Hafiz Muhammad
;
An Dinh, Van
;
Zhao, Yang
;
Wang, Shuanhu
The increasing demand of energy storage devices has developed an urgent need of rechargeable batteries. Sodium ion batteries (SIBs) may have potential to replace lithium ion batteries (LIBs) due to their low cost, high abundance and safety. Herein, the structural, electrochemical and electronic characteristics of two dimensional (2D) SnC monolayer for anodic applications are determined using the density functional method. The electronic structure of pristine SnC demonstrates the indirect-gap semiconducting character with a band gap of 1.72 eV and 0.92 eV using HSE06 and GGA-PBE approximations, respectively. After insertion of small amount of Na, the semiconductor to semi-metallic transition is observed. Moreover, the low open circuit voltage (0.24 V) and theoretical capacity (205 mAg/h) for SnC monolayer are also observed. The low diffusion barrier (0.17 eV) assists in charging-discharging process. The outcomes of our study suggest the SnC monolayer could be an efficient anode material for SIBs.
Publicationtype: Journal Article
5
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Controlling transport properties at LaFeO₃/SrTiO₃interfaces by defect engineering
(2021-06-01)
Butt, Mehwish Khalid
;
Zeeshan, Hafiz Muhammad
;
Zhao, Yang
;
Wang, Shuanhu
;
Jin, Kexin
The formation of conductive LaFeO₃/SrTiO₃ interfaces is first time reported by pulsed laser deposition via controlling the defects of SrTiO₃, which are closely related to the surface of substrate. It is found that the interfaces grown on SrTiO₃ substrates without terraces exhibit the two dimensional electron gas. Moreover, the conductive interfaces show a resistance upturn at low temperatures which is strongly diminished by light irradiation. These interfaces favor the persistent photoconductivity, and the enormous value of relative change in resistance, about 60 185.8%, is also obtained at 20 K. The experimental results provide fundamental insights into controlling the defects at conductive interfaces of oxides and paving a way for complex-oxides based optoelectronic devices.
Publicationtype: Journal Article
5
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High breakdown voltage in La0.7Sr0.3MnO₃/LaAlO₃/SrTiO₃ heterostructures
(American Institute of Physics (AIP), 2020-12-28)
Zeeshan, Hafiz Muhammad
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Butt, Mehwish Khalid
;
Wang, Shuanhu
;
Rafiq, Mubashar
;
Jin, Kexin
The junction diode as a high-voltage rectifier has a great impact within the electronic industry because of its applications. It has been synthesized accommodating two dimensional materials, [Sahatiya et al., 2D Mater. 4(2), 025053 (2017)]. Si-based p-n junctions and Si-based heterostructures in combination with complex oxides [Zhao et al., Appl. Phys. Lett. 93(25), 252110 (2008)]. In this Letter, we have synthesized the p-i-n junction using complex oxides La0.7Sr0.3MnO₃ (LSMO), LaAlO₃ (LAO), and SrTiO₃ (STO), which exhibits the rectifying behavior as Si-based heterostructures in combination with complex oxides. In addition, the light-induced weak localization effect is observed in the LSMO film. This research will further assist in the growth of the electronic industry of STO-based heterostructures.
Publicationtype: Journal Article
8

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