Undoped and Zn-doped SnO sub(2) thin films are deposited onto glass substrates by sol-gel spin coating method. All the films are characterized by X-ray photon spectroscopy (XPS) and Fourier transform ...infra-red spectroscopy (FTIR). XPS shows that Sn presence as valence of Sn super(4+) in the prepared SnO sub(2) thin films instead of Sn super(2+). In addition, it also exhibits the amount of Zn in SnO sub(2) thin films, which increases with increasing Zn doping percentage. The Zn (2P sub(3/2)) peak is symmetric and centred at around 1,021.73 eV which shifts to the lower binding energy of 1,020.83 eV for 15 at.% Zn doped SnO sub(2) thin film. FTIR study is used to describe the local environment of undoped and Zn-doped SnO sub(2) thin films which also confirms the synthesis of undoped and Zn-doped SnO sub(2) thin films. It is found that the resistance of SnO sub(2) thin films increases as Zn doping concentration increases at room humidity. The resistance of all the samples increases as relative humidity (RH) increases. The sensitivity of SnO sub(2) thin films increases as RH increases while it decreases as Zn doping percentage increases. Response time of SnO sub(2) thin film decreases as Zn doping percentage increases and recovery time slightly increases with doping percentage.
Owing to their excellent physical properties, atomically thin layers of molybdenum disulfide (MoS2) have recently attracted much attention due to their nonzero‐gap property, exceptionally high ...electrical conductivity, good thermal stability, and excellent mechanical strength, etc. MoS2‐based devices exhibit great potential for applications in optoelectronics and energy harvesting. Here, a comprehensive review of various doping strategies is presented, including wet doping and dry doping of atomically crystalline MoS2 thin layers, and the progress made so far for their doping‐based prospective applications is also discussed. Finally, several significant research issues for the prospects of doped‐MoS2 in industry, as a guide for 2D material community, are also provided.
Various strategies for doping of molybdenum disulfide are comprehensively reviewed, including wet doping and dry doping of MoS2 thin layers and the progress made so far for their doping‐based industrial applications. Finally, a few important opening study directions for future prospects of doped atomically crystalline MoS2 layers in optoelectronics and energy harvesting, as a guide for the 2D material community, are also provided.
Selective doping of a single conjugated polymer (CP) to obtain p‐type and n‐type conductive materials would be highly attractive for organic thermoelectric applications, because it will greatly ...reduce the time and costs of synthesizing different types of CPs. However, this strategy has rarely been investigated. In this study, two CPs are synthesized, designated PTQDPP‐T and PTQDPP‐2FT, based on a newly developed quinoidal unit with thienoisatin as the termini and a thiophene‐flanked diketopyrrolopyrrole (ThDPP) unit as the quinoidal core. The electron‐rich thiophene rings in thienoisatin and the electron delocalization induced by thienoisatin resulted in polymers with high‐lying highest occupied molecular orbital, and the electron‐deficient nature of ThDPP unit and its quinoidal backbone endowed the polymers with low‐lying lowest unoccupied molecular orbitals. As a result, both polymers can be p‐type and n‐type doped. Because of its high mobility, doped PTQDPP‐2FT performed better in organic thermoelectric devices than the doped PTQDPP‐T. After being doped with FeCl3 and N‐DMBI, PTQDPP‐2FT showed p‐type and n‐type power factors of 278.2 and 2.37 µW m−1 K−2, respectively. These are the best for bipolar (p‐type and n‐type) performances that obtained by selective doping of a single polymer.
Polymers that can be both p‐doped and n‐doped are synthesized via incorporating a thienoisatin terminated quinoidal unit. Organic thermoelectric devices with a p‐type power factor >270 µW m−1 K−2 and an n‐type power factor >2 µW m−1 K−1 are fabricated by selective doping the polymers with FeCl3 and N‐DMBI, respectively.
Abstract
A new facile route to fabricate N‐doped graphene‐SnO
2
sandwich papers is developed. The 7,7,8,8‐tetracyanoquinodimethane anion (TCNQ
−
) plays a key role for the formation of such ...structures as it acts as both the nitrogen source and complexing agent. If used in lithium‐ion batteries (LIBs), the material exhibits a large capacity, high rate capability, and excellent cycling stability. The superior electrochemical performance of this novel material is the result from its unique features: excellent electronic conductivity related to the sandwich structure, short transportation length for both lithium ions and electrons, and elastomeric space to accommodate volume changes upon Li insertion/extraction.
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•An efficient Co3O4 catalyst is engineered by Mg doping and partial de-doping.•The obtained catalyst shows multiple surface and structure defects.•The defective Co3O4 could lower the ...HCHO activation energy barrier.•Excellent HCHO oxidation activity is achieved over the defective Co3O4.
The pursuit of high-performance non-precious metal catalysts for Volatile Organic Compounds (VOCs) abatement is paramount in meeting stringent environmental regulations. In this study, we present a groundbreaking approach by crafting a highly defective Co3O4 catalyst through a strategic process involving Mg doping and subsequent partial de-doping. The catalyst exhibited an exceptional activity in the oxidation of formaldehyde (HCHO), achieving a remarkable conversion rate of 2.92 μmol·m−2·h−1, which is 3.1 times that of the pristine Co3O4 at 100 °C and an HCHO space velocity of 75,000 mL·g−1·h−1. Our methodology involves a dual-action process of doping and de-doping, orchestrating the introduction of significant structural and surface defects. These include surface cracks, lattice distortions, cationic vacancies, oxygen vacancies, lower metal coordination, and more. This orchestrated creation of defects serves to amplify the generation of active oxygen sites, thereby enhancing the intrinsic oxidative ability of the catalyst. The net result is a lowered activation energy barrier for HCHO, further contributing to the catalyst performance enhancement. This study not only establishes a new benchmark for Co3O4 catalysis but also provides insightful paradigms for the role of defects engineering in promoting non-noble metal-catalyzed volatile organic compounds oxidation.
Hydrogen (H2) production from direct seawater electrolysis is an economically appealing yet fundamentally and technically challenging approach to harvest clean energy. The current seawater ...electrolysis technology is significantly hindered by the poor stability and low selectivity of the oxygen evolution reaction (OER) due to the competition with chlorine evolution reaction in practical application. Herein, iron and phosphor dual‐doped nickel selenide nanoporous films (Fe,P‐NiSe2 NFs) are rationally designed as bifunctional catalysts for high‐efficiency direct seawater electrolysis. The doping of Fe cation increases the selectivity and Faraday efficiency (FE) of the OER. While the doping of P anions improves the electronic conductivity and prevents the dissolution of selenide by forming a passivation layer containing P–O species. The Fe‐dopant is identified as the primary active site for the hydrogen evolution reaction, and meanwhile, stimulates the adjacent Ni atoms as active centers for the OER. The experimental analyses and theoretical calculations provide an insightful understanding of the roles of dual‐dopants in boosting seawater electrolysis. As a result, a current density of 0.8 A cm−2 is archived at 1.8 V with high OER selectivity and long‐term stability for over 200 h, which surpasses the benchmarking platinum‐group‐metals‐free electrolyzers.
An ultrahigh activity and selectivity seawater electrolyzer with robust stability is developed via a dual‐doping and synergism optimization of Fe,P‐NiSe2 nanoporous films. The Fe cation increases the selectivity and Faraday efficiency, while the P anion improves the electronic conductivity and prevents the dissolution of selenide.
Several beneficial features maintain TiO2 in the top list of viable materials for photocatalytic purposes. However, its relatively large band-gap (3.0–3.2 eV) still hampers practical applications ...under sunlight. This work explores Direct Current (DC) Plasma Electrolytic Oxidation (PEO) of titanium as a fast, easily-scalable and single-step tool to synthesise doped TiO2 photoanodes with controlled morphology, crystalline structure and thickness. Zn-, Cu- and Fe-doped crystalline TiO2 films were obtained in H2SO4 aqueous solutions containing ZnSO4, CuSO4 and FeSO4 precursors, respectively. As-prepared TiO2 films showed a porous and homogeneous sponge-like surface morphology, typical of PEO-produced oxides, and a crystalline phase structure consisting of a mixture of anatase and rutile phases. The anatase content varied in the 54–100 % range and correspondingly the band-gap energy was in the 2.85–3.07 eV range. Doped oxides prepared with a low concentration of the metal precursors showed monochromatic incident-photon-to-current-efficiency (IPCE) values exceeding those obtained with pristine TiO2 by up to 24 %, best performing in the order Zn- > Cu- > Fe-doped TiO2. Photocurrent under polychromatic UV-Vis irradiation showed an analogous trend and the estimated efficiency of solar-light harvesting was in the 0.3–4 % range, with Zn- ≈ Cu- > Fe-doped TiO2. Although the superior performance of the PEO-prepared metal-doped TiO2 could not be fully confirmed by photoelectrocatalytic oxidation tests of organics, the present investigation showed the viability of DC PEO for the synthesis of metal-doped TiO2 photoanodes.
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•Zn, Cu, Fe doped crystalline TiO2 films obtained by plasma electrolytic oxidation.•Best photoeletrochemical activity at low doping levels.•IPCE and LSV values exceeding pristine TiO2.•No straightforward correlation between photoelectrochemical and catalytic activity.
Improving the capacitance of carbon materials for supercapacitors without sacrificing their rate performance, especially volumetric capacitance at high mass loadings, is a big challenge because of ...the limited assessable surface area and sluggish electrochemical kinetics of the pseudocapacitive reactions. Here, it is demonstrated that “self‐doping” defects in carbon materials can contribute to additional capacitance with an electrical double‐layer behavior, thus promoting a significant increase in the specific capacitance. As an exemplification, a novel defect‐enriched graphene block with a low specific surface area of 29.7 m2 g−1 and high packing density of 0.917 g cm−3 performs high gravimetric, volumetric, and areal capacitances of 235 F g−1, 215 F cm−3, and 3.95 F cm−2 (mass loading of 22 mg cm−2) at 1 A g−1, respectively, as well as outstanding rate performance. The resulting specific areal capacitance reaches an ultrahigh value of 7.91 F m−2 including a “self‐doping” defect contribution of 4.81 F m−2, which is dramatically higher than the theoretical capacitance of graphene (0.21 F m−2) and most of the reported carbon‐based materials. Therefore, the defect engineering route broadens the avenue to further improve the capacitive performance of carbon materials, especially for compact energy storage under limited surface areas.
Owing to the significantly improved double‐layer capacitance originating from the “self‐doping” defects, defective graphene blocks with high defect density (ID/IG = 2.16), high packing density (0.917 g cm–3), and low specific surface area (29.7 m2 g–1) show an integration of high gravimetric, volumetric, and areal capacitances for supercapacitors.
Cesium‐based inorganic perovskites, such as CsPbI2Br, are promising candidates for photovoltaic applications owing to their exceptional optoelectronic properties and outstanding thermal stability. ...However, the power conversion efficiency of CsPbI2Br perovskite solar cells (PSCs) is still lower than those of hybrid PSCs and inorganic CsPbI3 PSCs. In this work, passivation and n‐type doping by adding CaCl2 to CsPbI2Br is demonstrated. The crystallinity of the CsPbI2Br perovskite film is enhanced, and the trap density is suppressed after adding CaCl2. In addition, the Fermi level of the CsPbI2Br is changed by the added CaCl2 to show heavy n‐type doping. As a result, the optimized CsPbI2Br PSC shows a highest open circuit voltage of 1.32 V and a record efficiency of 16.79%. Meanwhile, high air stability is demonstrated for a CsPbI2Br PSC with 90% of the initial efficiency remaining after more than 1000 h aging in air.
Herein, calcium chloride is applied to passivate and dope inorganic CsPbI2Br. It enhances the crystallinity of CsPbI2Br to decrease trap density and prolong carrier lifetime and to raise its Fermi level to lie very close to the conduction band, leading to a high voltage of 1.32 V, and a record efficiency of 16.79% for CsPbI2Br cells.
