•Core-shell CoFe2O4@ZnIn2S4 p-n heterojunction wassuccessfullysynthesized for the first time.•The CoFe2O4@ZnIn2S4-2 photocatalyst exhibited an outstanding hydrogen evolution rate, excellent cycle ...application and chemical stability.•The Z-Scheme mechanism of CoFe2O4@ZnIn2S4 in photocatalytic hydrogen production has been discussed in detail.
The p-n heterojunction’s construction is considered a valid and prominent method to accelerate photogenerated carriers’ separation and transfer rate, enhancing the efficiency of photocatalytic hydrogen production. In this work, the core–shell CoFe2O4@ZnIn2S4 (CFO@ZIS) p-n heterojunction photocatalyst is designed and fabricated by growing ZIS nanosheets on yolk-shelled CFO surfaces by hydrothermal and calcination method followed by oil bath process for the first time. Notably, the CFO@ZIS-2 photocatalyst exhibits excellent cycle applicability and chemical stability and exhibits a remarkable hydrogen evolution rate of 1576.5 μmol∙g−1∙h−1 without Pt as a co-catalyst. However, the hydrogen evolution rates of pristine ZIS and CFO products are just 344.3 and 0 μmol∙g−1∙h−1, respectively. Furthermore, the analysis of structural, morphological, optical and photo/electrochemical characterizations further manifested the existence of p-n heterojunction in CFO@ZIS core–shell structure is beneficial to facilitate the separation and migration of photoinduced carriers. Meanwhile, the Z-Scheme mechanism of CFO@ZIS p-n heterojunction in photocatalytic hydrogen production has been discussed in detail. This work provides a feasible and resultful strategy to design the core–shell p-n heterojunction for the promotion of photocatalytic H2 production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study examines the impact of International Financial Reporting Standards (IFRS) adoption on audit fees. We first build an analytical audit fee model to analyze the impact on audit fees for the ...change in both audit complexity and financial reporting quality brought about by IFRS adoption. We then test the model's predictions using audit fee data from European Union countries that mandated IFRS adoption in 2005. We find that mandatory IFRS adoption has led to an increase in audit fees. We also find that the IFRS-related audit fee premium increases with the increase in audit complexity brought about by IFRS adoption, and decreases with the improvement in financial reporting quality arising from IFRS adoption. Finally, we find some evidence that the IFRS-related audit fee premium is lower in countries with stronger legal regimes. Our results are robust to a variety of sensitivity checks.
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BFBNIB, CEKLJ, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A complete mechanistic study on the nucleation of polymeric nanoparticles covering the generation of the clusters and the forthcoming aggregation to the nuclei is performed by in situ 1H nuclear ...magnetic resonance (NMR) experiments using polyaniline as an example. An aniline tetramer and a monomer-stabilized nitrenium are proved to be the basic cluster and predominant propagating intermediate in the nucleation. It is observed that the nuclei are generated via a sequential mechanism involving a translocation of the protonated tetramers to the aqueous bulk, dissociation of sodium dodecyl sulfate (SDS) micelles, and deprotonation to induce the fusion of the dissociated micelles and intermolecular packing of the oligomers. Despite its importance, direct observation of the nucleation is challenging. This work emphasizes the importance of utilizing the solvent in solvation shell as the sensitive probe to explore the most transient process in nucleation, demonstrating its efficiency in achieving information such as the stepwise procedures, the nuclei sizes, the growth kinetics, and so forth. The approach reported herein may prove of great value in establishing the missing link of the atomic origin of nanoparticles, a key topic toward the preparation of functional nanostructures with well-controlled architectures, and can be readily extended to the study of other organic or inorganic systems.
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IJS, KILJ, NUK, PNG, UL, UM
Uniform silver quantum dots decorated TiO
2
nanotubes (Ag-TiO
2
NTs) were synthesized via a simple reduction reaction in ethanol solvent. The size distribution of composite NTs arranges from 3 to ...5 nm for Ag quantum dots and about 10 nm for TiO
2
NTs in diameter. The composite Ag-TiO
2
nanoparticles were incorporated in organic hybrid solar cells through doping into the active layer. Both the optical and electrical properties of the solar cells were improved. The photocurrent and fill factor of the devices were obviously increased after the Ag-TiO
2
NTs were introduced, accompanied with a greatly reduced series resistance as well as enlarged shunt resistance. Suppressed recombination due to efficient charge transfer from plasmonic Ag quantum dots to the attached TiO
2
NTs made contribution to the charge collection and transportation so that the fill factor was increased. Meanwhile, the enhanced light absorption resulted from effective incident light scattering by the Ag-TiO
2
NTs composite played a role in increasing photocurrent. As a result, solar cells with Ag-TiO
2
NTs generated an enhanced conversion efficiency up to 20 and 50 % compared to that adopting TiO
2
NTs and that without doping, respectively.
Organic-inorganic halide perovskites are promising semiconductors to mate with silicon in tandem photovoltaic cells due to their solution processability and tunable complementary bandgaps. Herein, we ...show that a combination of two additives, MACl and MAH2PO2, in the perovskite precursor can significantly improve the grain morphology of wide-bandgap (1.64–1.70 eV) perovskite films, resulting in solar cells with increased photocurrent while reducing the open-circuit voltage deficit to 0.49–0.51 V. The addition of MACl enlarges the grain size, while MAH2PO2 reduces non-radiative recombination through passivation of the perovskite grain boundaries, with good synergy of functions from MACl and MAH2PO2. Matching the photocurrent between the two sub-cells in a perovskite/silicon monolithic tandem solar cell by using a bandgap of 1.64 eV for the top cell results in a high tandem Voc of 1.80 V and improved power conversion efficiency of 25.4%.
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•Synergistic effects of additives create large grains and low defect density•1.80 V tandem device enabled by a 1.64-eV perovskite with Voc deficit of 0.49 V•25.4%-efficient monolithic perovskite/Si tandem device
The efficiency of organic-inorganic halide perovskite solar cells skyrocketed in the past 6 years, reaching 23.3%. Their pairing with silicon in tandem solar cells offers a promising path for further reducing the levelized cost of electricity of photovoltaics. Strategies such as compositional engineering and charge-transport-layer optimization have been reported to improve the tandem efficiency. However, the large open-circuit voltage deficit of wide-bandgap perovskite cells still limits the tandem performance. Here, we utilize combined additives to smooth the perovskite film, increase its grain size, and lower its defect density. The synergistic effect of the additives leads to increased photocurrent and reduced open-circuit voltage deficit for wide-bandgap perovskite solar cells. When additives are used to form a top cell with a bandgap of 1.64 eV, the perovskite and silicon sub-cells are current matched and yield a perovskite/silicon tandem device with an efficiency of 25.4%.
Grain engineering through combined MACl and MAH2PO2 additives in perovskite precursors improves the photovoltaic performance of perovskite/silicon tandem cells. MACl increases the grain size of wide-bandgap perovskite films and also produces smooth films. MAH2PO2 suppresses non-radiative recombination sites at grain boundaries. The synergetic effects of MACl and MAH2PO2 further promote grain growth and prolong the carrier recombination lifetime. This enables a power conversion efficiency of 25.4% for a perovskite/silicon tandem device.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•g-C3N4/BFCTO synthesized by a facile chemical process for the first time.•g-C3N4/BFCTO exhibit favorable visible-light photocatalytic property.•Under visible-light irradiation, ...g-C3N4/BFCTO follows a Z-scheme mechanism.
Construction of heterostructure is an efficient approach to improve the photocatalytic performance of catalysts. Herein, the Bi6Fe1.5Co0.5Ti3O18 (BFCTO) nanoplates are successfully loaded on g-C3N4 nanosheets by a facile chemical process for the first time. The photocatalytic activity of all g-C3N4/BFCTO catalysts are measured by the degradation of Rhodamine B (RhB) under visible-light irradiation. The results display that g-C3N4/BFCTO heterojunctions exhibit greatly improved photocatalytic activity compared with corresponding bare g-C3N4 and BFCTO catalysts. Based on the experimental results of photocurrent responses, EIS and ESR, it is clearly demonstrated that the improved activity is attributed to the formation of Z-scheme photocatalyst. The g-C3N4/BFCTO-2 heterojunction showed the optimal photocatalytic activity with the photodegradation efficiency of 84.9% within 20 min. We hope that the work can provide a new insight for exploring Bin+1Fen−3Ti3O3n+3-based Z-scheme heterojunction for pollutant degradation and environment restoration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•α-Fe2O3/x%SiO2 (x = 0, 10, 15, 20, 30) were synthesized for the first time by sol-gel method.•The α-Fe2O3/20 %SiO2 had a good sensing response to acetone at 290 °C.•The α-Fe2O3/20 ...%SiO2 nanocomposite showed good sensitive and selective detection of acetone.•The α-Fe2O3/20 %SiO2 nanocomposite showed gas sensor response about 34 times higher than that of pure α-Fe2O3.
Herein, a novel gas-sensing nanocomposite of α-Fe2O3/x%SiO2 (x = 0, 10, 15, 20, 30) was synthesized for the first time by sol-gel. With an increase in SiO2 concentration to 30 %, the average crystallite size and pore-size distribution of samples exhibited a decreasing trend. The surface area also showed an increasing trend with the introduction of SiO2. Gas-sensing measurement results revealed that the α-Fe2O3/20 %SiO2 nanocomposite showed the highest response (Ra/Rg = 50.20) to 500 ppm acetone at its optimal operating temperature of 290 °C, which was about 34 times higher than that of the pure α-Fe2O3 gas sensor. The response/recovery time of the α-Fe2O3/20 %SiO2-based sensor to 500 ppm acetone was 14 s/7 s. The response/recovery time of α-Fe2O3 was 25 s/21 s. After SiO2 was modified, the response/recovery speed increased. The results demonstrated the potential of α-Fe2O3/20 %SiO2-based gas sensors for sensitive and selective detection of acetone.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this work, W6+ ions doped Bi2MoO6:20%Yb3+, 2%Er3+ samples were successfully synthesized by a facile and modified hydrothermal method. The main morphology of Bi2MoO6 samples were hollow microsphere ...structure assembled by nanosheets. The particle size was slightly increased as enhancing W6+ ions doping concentration to 5%, then decreased as the doping concentration increased. Besides, doping W6+ ions can increase the band gap of products from 2.65 eV to 2.71eV. The upconversion emission intensity of all samples was strongly influenced by the W6+ ions doping concentration. The luminescent intensity enhanced with the doping concentration increasing up to 3%, then decreased when the W6+ ions concentration further increased. Moreover, the intensity of red emission increased by a large margin than that of green-light region. Besides, the lifetime of 4F9/2 states of Er3+ ions for Bi2MoO6:20%Yb3+, 2%Er3+, 3%W6+ (τ655 = 583.64 μs) had significant longer lifetime relative to the Bi2MoO6:20%Yb3+, 2%Er3+ (τ655 = 70.29 μs).
Hollow microsphere structure Bi2MoO6:20%Yb3+, 2%Er3+, x% W6+ samples were successfully synthesized by a facile and modified hydrothermal method. The upconversion emission intensity of all samples was strongly influenced by the W6+ ions doping concentration. Display omitted
•W6+ doped Bi2MoO6:20%Yb3+, 2%Er3+ samples were synthesized by hydrothermal method.•The main morphology was hollow microsphere structure assembled by nanosheets.•The particle sizes and band gaps depended on W6+ ions doping concentration.•The upconversion emission intensity obtained the maximum when W6+ doping concentration is 3%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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