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.
Display omitted
•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.
A controllable and area selective doping process, especially for p-type Molybdenum disulphide (MoS 2 ), is essential for the realization of various p/n junction-based devices. In this work, we ...demonstrate p-type doping of multilayer MoS 2 with phosphorus (P) as a dopant using a CMOS-compatible plasma immersion ion implantation (PIII) technique. Detailed physical characterization including XPS and SIMS, backed with ab-initio DFT calculations, confirms p-type doping in P-implanted MoS 2 that could be due to a combination of surface charge transfer from physisorbed phosphine ions and/or substitutional phosphorus present in the top few (~5) layers. Controlled reduction in current levels and positive V T shifts were observed in channel-doped MoS 2 transistors. Further, selectively doped gated p/n-junction diodes (rectification ~50X) have been demonstrated.
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.
Display omitted
•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.
Asahi et al explore the designs, developments and prospects of nitrogen-doped titanium dioxide as a visible-light-sensitive photocatalyst. They focus on topics such as the materials design for ...visible-light-sensitive photocatalyst, the synthesis and properties of nitrogen-doped titanium dioxide (TiO2), and the detailed analysis of N-doped TiO2.
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.
Photocatalytic degradation of dye and phenolic compounds as textile effluent using UV- TiO2 photocatalysis based on color removal.
Display omitted
•TiO2 is used as a semiconductor photocatalyst in ...presence of UV light.•TiO2 photocatalytic advanced oxidation process is executed by five steps.•Metal and non-metal co-doping on TiO2 can increase photocatlytic performance.•UV- doped TiO2 photocatalysis is able to mineralize toxic dyes and phenolic compounds.
Treatment of textile wastewater using titanium dioxide (TiO2) photocatalysis has been started from the last decade and reached attention to the researchers because of its versatile application. The variety of applications of TiO2 as a photocatalyst has been taken place because of low operating temperature, biologically inert nature, low energy consumption, water insolubility, ease availability and photoactivity, less toxicity, high chemical stability, suitable flat band potential, narrow band gap and environmentally benign. The successful and efficient application of photocatalysis depends on quality of photocatalyst, nature of pollutants, and source of light, which should be in close contact with each other. The TiO2 photocatalyst is used for the effluent treatment of textile wastewater in the presence of ultraviolet (UV) irradiation. Heterogeneous UV-TiO2 photocatalysis is capable to remove organic pollutants from textile wastewater, which has been widely studied and the technology also being commercialized in many developing countries in the world. This review focuses on the mechanism of UV-TiO2 photocatalysis, modification of TiO2 photocatalyst, and application of doping and co-doping in order to improve the photocatalytic activity in wastewater treatment. In addition, the review conveys comprehensive and fundamental assessments of the photocatalytic activity for the removal of organic dyes and phenolic compounds from textile wastewater.
