We herein demonstrate self-doping of the CO32– anionic group into a wide bandgap semiconductor Bi2O2CO3 realized by a one-pot hydrothermal technique. The photoresponsive range of the self-doped Bi2O2CO3 can be extended from UV to visible light and the band gap can be continuously tuned. Density functional theory (DFT) calculation results demonstrate that the foreign CO32– ions are doped in the caves constructed by the four adjacent CO32– ions and the CO32– self-doping can effectively narrow the band gap of Bi2O2CO3 by lowering the conduction band position and meanwhile generating impurity level. The photocatalytic performance is evaluated by monitoring NO removal from the gas phase, photodegradation of a colorless contaminant (bisphenol A, BPA) in an aqueous solution, and photocurrent generation. In comparison with the pristine Bi2O2CO3 which is not sensitive to visible light, the self-doped Bi2O2CO3 exhibits drastically enhanced visible-light photoreactivity, which is also superior to that of many other ...

Anionic Group Self-Doping as a Promising Strategy: Band-Gap Engineering and Multi-Functional Applications of High-Performance CO32–-Doped Bi2O2CO3

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...

Compound Copper Chalcogenide Nanocrystals

Because of the interesting and multifunctional properties, recently, ZnO nanostructures are considered as excellent material for fabrication of highly sensitive and selective gas sensors. Thus, ZnO nanomaterials are widely used to fabricate efficient gas sensors for the detection of various hazardous and toxic gases. The presented review article is focusing on the recent developments of NO2 gas sensors based on ZnO nanomaterials. The review presents the general introduction of some metal oxide nanomaterials for gas sensing application and finally focusing on the structure of ZnO and its gas sensing mechanisms. Basic gas sensing characteristics such as gas response, response time, recovery time, selectivity, detection limit, stability and recyclability, etc are also discussed in this article. Further, the utilization of various ZnO nanomaterials such as nanorods, nanowires, nano-micro flowers, quantum dots, thin films and nanosheets, etc for the fabrication of NO2 gas sensors are also presented. Moreover, various factors such as NO2 concentrations, annealing temperature, ZnO morphologies and particle sizes, relative humidity, operating temperatures which are affecting the NO2 gas sensing properties are discussed in this review. Finally, the review article is concluded and future directions are presented.

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Zinc Oxide Nanostructures for NO2 Gas–Sensor Applications: A Review

The constructing of direct solid-state Z-scheme heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, a novel direct solid-state Z-scheme V2O5/g-C3N4 heterojunctions were synthesized via a facile in-situ growth strategy for the first time. The photocatalytic performance was evaluated by the degradation of rhodamine B (RhB) and tetracycline (TC) under visible light irradiation (λ > 420 nm). Results show that the as-synthesized heterojunctions can significantly enhance photocatalytic activity in comparison with pure g-C3N4 and V2O5. The optimum photocatalytic efficiency of VC1.0% sample for the degradation RhB was about 7.3 and 13.0 times higher than that of individual g-C3N4 and V2O5, respectively. In addition, the VC1.0% sample as well as can efficiently degrade methyl orange (MO) and methylene blue (MB) under visible light. By further experimental study, the possible for the enhancing photocatalytic mechanism was found to be a direct solid-state Z-scheme heterojunction system based on the active species trapping and electron spin resonance (ESR) experiments, which not only can improve the photogenerated electron–hole pair’s separation but also exhibit a strong oxidation and reduction ability for efficiency degradation of organic pollutants. This work will be useful for the design of other direct solid-state Z-scheme photocatalytic systems for application in energy conversion and environmental remediation.

In-situ synthesis of direct solid-state Z-scheme V2O5/g-C3N4 heterojunctions with enhanced visible light efficiency in photocatalytic degradation of pollutants

Intricate hollow structures garner tremendous interest due to their aesthetic beauty, unique structural features, fascinating physicochemical properties, and widespread applications. Here, the recent advances in the controlled synthesis are discussed, as well as applications of intricate hollow structures with regard to energy storage and conversion. The synthetic strategies toward complex multishelled hollow structures are classified into six categories, including well-established hard- and soft-templating methods, as well as newly emerging approaches based on selective etching of “soft@hard” particles, Ostwald ripening, ion exchange, and thermally induced mass relocation. Strategies for constructing structures beyond multishelled hollow structures, such as bubble-within-bubble, tube-in-tube, and wire-in-tube structures, are also covered. Niche applications of intricate hollow structures in lithium-ion batteries, Li–S batteries, supercapacitors, Li–O2 batteries, dye-sensitized solar cells, photocatalysis, and fuel cells are discussed in detail. Some perspectives on the future research and development of intricate hollow structures are also provided.

Intricate Hollow Structures: Controlled Synthesis and Applications in Energy Storage and Conversion

Ag2O/Bi2O2CO3 p-n heterojunctions are prepared with commercial Bi2O2CO3 as precursor via a simple photosynthesis process. The obtained Ag2O/Bi2O2CO3 p-n heterojunctions show higher photocatalytic activity than that of pure n-Bi2O2CO3, and the obtained Ag2O/Bi2O2CO3 (AB-4) heterojunction exhibits the best photocatalytic activity under visible light (λ > 400 nm), with which Rhodamine B, methyl blue and methyl orange can be completely degraded within 12 min. Photoluminescent spectra and photoelectrochemical measurement further indicate that the Ag2O/Bi2O2CO3 p-n heterojunctions greatly enhance the charge generation and suppress the charge recombination of photogenerated electron–hole pairs, which would be beneficial to improve their photocatalytic activity.

Highly Efficient Ag2O/Bi2O2CO3 p-n Heterojunction Photocatalysts with Improved Visible-Light Responsive Activity

Novel Bi2S3/Bi2O2CO3 heterojunction photocatalysts were prepared by a simple chemical reaction from commercial Bi2O2CO3. The photocatalytic activities of Bi2S3/Bi2O2CO3 were evaluated by degrading Rhodamine B (RhB) under visible light and sunlight irradiation. Further investigation revealed that the content of loading bismuth sulfide (Bi2S3) had important effects on the photocatalytic activity of the Bi2S3/Bi2O2CO3 heterojunctions, and the 5 mol% Bi2S3/Bi2O2CO3 heterojunction photocatalyst exhibited the best photocatalytic activity (30 min under visible light, λ > 400 nm). The high photocatalytic activity could be attributed to its good visible light absorption, facilitated charge separation of photogenerated electron–hole pairs and efficient charge transfer path in the partly exposed core in the heterojunctions. These benefits are derived from the unique band gap structure of the Bi2S3/Bi2O2CO3 n–n-type heterojunctions and special morphology with the partly exposed core, which was confirmed by photoluminescent spectra, surface photovoltage spectra and photoelectrochemical characterizations.

Novel Bi2S3/Bi2O2CO3 heterojunction photocatalysts with enhanced visible light responsive activity and wastewater treatment

In most of the reported n-n heterojunction photocatalysts, both the conduction and valence bands of one semiconductor are more negative than those of the other semiconductor. In this work, we designed and synthesized a novel n-n heterojunction photocatalyst, namely CdS-ZnWO4 heterojunctions, in which ZnWO4 has more negative conduction band and more positive valence band than those of CdS. The hydrogen evolution rate of CdS-30 mol %-ZnWO4 reaches 31.46 mmol h(-1) g(-1) under visible light, which is approximately 8 and 755 times higher than that of pure CdS and ZnWO4 under similar conditions, respectively. The location of the surface active sites is researched and a plausible mechanism of performance enhancement by the tuning of the structure is proposed based on the photoelectrochemical characterization. The results illustrate that this kind of nonconventional n-n heterojunctions is also suitable and highly efficient for solar hydrogen evolution.

Rationally Designed n–n Heterojunction with Highly Efficient Solar Hydrogen Evolution

Rose-like I-doped Bi2O2CO3 microspheres with enhanced visible light response: DFT calculation, synthesis and photocatalytic performance.

Well-defined uniform pyramidal Ag-Ag8SnS6 heterodimers are prepared via a one-pot method. A plausible formation mechanism for the unique structures based on a seed-growth process and an etching effect due to oleylamine is proposed. The formed metal-semiconductor Mott-Schottky heterojunction promotes electron transfer from semiconducting Ag8 SnS6 to metallic Ag, which catalyzes the reduction of I3 (-) to I(-). When used as counter electrode in dye-sensitized solar cells, the heterodimers show comparable performance to platinum.

Na Liang

Papers

Highly Efficient Ag2O/Bi2O2CO3 p-n Heterojunction Photocatalysts with Improved Visible-Light Responsive Activity

Novel Bi2S3/Bi2O2CO3 heterojunction photocatalysts with enhanced visible light responsive activity and wastewater treatment

Rationally Designed n–n Heterojunction with Highly Efficient Solar Hydrogen Evolution

Rose-like I-doped Bi2O2CO3 microspheres with enhanced visible light response: DFT calculation, synthesis and photocatalytic performance.

The Role of Mott–Schottky Heterojunctions in Ag–Ag8SnS6 as Counter Electrodes in Dye‐Sensitized Solar Cells