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排序方式: 共有637条查询结果,搜索用时 234 毫秒
81.
《International Journal of Hydrogen Energy》2022,47(1):228-241
The construction of semiconductor heterojunction for photocatalytic H2 production from water splitting is an efficient and environment-friendly technology. In this work, ZnO/BiOCl (ZBC) and Sn-doped ZnO/BiOCl (ZBC-S) photocatalysts with Z-scheme heterojunction were successfully prepared by simple hydrothermal method. The photocatalytic H2 evolution from water splitting by the as-prepared photocatalysts was investigated. The formation of ZnO/BiOCl heterojunction reduces the recombination probability of the photogenerated carriers. The impurity levels originated from Sn doping reduce the band gap width of ZnO and BiOCl to some extent, thereby enhancing the light absorption ability. The ZBC-S composite exhibits the best photocatalytic activity. In addition, the photocatalytic efficiency of H2 production was improved by sensitization with Eosin Y (EY) dye. The H2 production rate under simulated sunlight reaches 4146.77 μmol g?1 h?1, which is 27 times higher than that of pure ZnO. Finally, the Z-scheme electron transfer route in ZnO/BiOCl heterojunction was determined, and the photocatalytic H2 production mechanism of EY sensitized ZBC-S was proposed. 相似文献
82.
《International Journal of Hydrogen Energy》2022,47(55):23310-23315
Alkaline aqueous solution of sodium borohydride NaBH4 (denoted SB-fuel) is an indirect fuel when it is used to generate H2 by hydrolysis, with the as-generated H2 feeding a fuel cell, and it is a direct fuel when it is an anodic fuel of a direct fuel cell. However, SB-fuel suffers from a major drawback: NaBH4 spontaneously hydrolyzes. Our study falls within this context. We studied the instability, at the NMR scale and over 12 weeks, of a series of SB-fuels (initial NaBH4 concentration from 3.65 to 31.22 wt%, NaOH concentration from 1 to 16 M, and temperature between ?15 and 60 °C) to find the conditions at which SB-fuel can be stored for weeks in relative safety. We found that SB-fuel with a NaOH concentration of ≥8 M is relatively stable under cold conditions (?15 and 4 °C). In these conditions, NaBH4 is not prevented from hydrolyzing, but the reaction is significantly mitigated. Otherwise, our study highlights the gaps in our understanding of the SB-fuel, emphasizes SB-fuel is a new concept of fuel (it should not be seen as any current fuel), and points out the challenges for attaining higher technology readiness levels. 相似文献
83.
《International Journal of Hydrogen Energy》2022,47(6):3781-3790
A novel heterostructure of g-C3N4/ZnO/Bi4O5Br2 (ZB-3) was designed, and used in the microbial coupled photocatalytic fuel cell (MPFC). It can effectively improve electron utilization efficiency and pollutant degradation using this double Z-scheme heterojunction structure. The current–time (I–t) curves demonstrated that the current density of ZB-3 was higher than that of ZnO, ZnO/Bi4O5Br2 (ZB-1), g-C3N4/ZnO (ZB-2). Electrochemical impedance spectroscopy (EIS) indicated ZB-3 possessed the minimum charge-transfer resistance. This MPFC for degrading rhodamine B (RhB) and tetracycline (TC) under different conditions were developed using these materials. Even in the dark condition, MPFC with g-C3N4/ZnO/Bi4O5Br2 demonstrated 93% and 82% degradation efficiency for RhB and TC, respectively. Furthermore, the electron transport mechanism of the MPFC and ZB-3 were proposed. It paves the approach for more efficient pollutant degradation via MFC photocatalysis. 相似文献
84.
《International Journal of Hydrogen Energy》2022,47(6):3857-3866
Ta3N5 has suitable band positions for visible light photocatalytic hydrogen production from water splitting. However, fast self-recombination of electrons and holes is a drawback for its low efficiency. A Ta3N5/WO3 Z-scheme was therefore considered to solve this problem. Furthermore, a nanohoneycomb (nHC) structure was designed and fabricated based on solution-based nanosphere lithography to offer higher surface area for reaction. The cell size of the nHC was controlled by using 400-, 200-, and 100-nm polystyrene nanospheres as the mask. Under visible light irradiation, the hydrogen generation rates of Ta3N5@WO3 film and Ta3N5@100-nm WO3 nHC were measured to be 4.6 and 8.1 μmol/g·h, respectively, whereas that of pure Ta3N5 nHC was negligible. With deposition of Pt cocatalyst, the hydrogen generation rates for Ta3N5@WO3 film and Ta3N5@100-nm WO3 nHC were further raised to 9.9 and 16.6 μmol/g·h, confirming the effectiveness of the structure design. 相似文献
85.
86.
《International Journal of Hydrogen Energy》2020,45(28):14334-14346
Developing low-cost, highly efficient and robust photocatalystic hydrogen evolution system is a promising solution to environmental and energy crisis. Herein, a Z-scheme Cu3P/ZnIn2S4 heterojunction photocatalyst was successfully constructed for the first time via a facile solution-phase hybridization method. The optimized Cu3P/ZIS composite exhibited the highest H2 production rate of 2561.1 μmol g−1 h−1 under visible light irradiation (>420 nm), which was 5.2 times greater than that of bare ZnIn2S4 and even exceeded the photocatalytic performance of Pt/ZIS composite. The apparent quantum yield of 10 wt% Cu3P/ZnIn2S4 can reach 22.3% at 420 nm. The huge boost of photocatalytic hydrogen evolution activity is ascribed to the formation of heterojunction with the built in electric field within Cu3P/ZnIn2S4 and Z-scheme charge carriers transfer pathway, which result in efficient separation and migration of charge carriers. In addition, both experimental and theoretical calculation confirmed that the charge-carriers transfer pathway of Cu3P/ZnIn2S4 photocatalyst follows the Z-scheme mechanism instead of conventional type-Ⅱ heterojunction mechanism. This work is considered helpful for getting a great deal of insight into constructing high-activity and cost-effective transition metal phosphides (TMPs) based photcatalytic hydrogen production system and rationally designing Z-scheme heterojunction photocatalyst. 相似文献
87.
《Geotextiles and Geomembranes》2022,50(1):163-173
Some of the main applications of geosynthetics include use as a hydraulic barrier in sanitary landfills, as a reinforcement element and in pavement engineering. In most cases, these materials are subject to the overlapping effects of tensile strength and puncture. This paper presents a review of indirect methods for calculation of stress and strain averages by means of the California Bearing Ratio (CBR) puncture strength test. In addition, a new calculation method is proposed based on the Kirchhoff plate theory, which interprets the behavior of thin circular plates subjected to a uniform normal loading. This new method enables analysis of the stress-strain in each stretch of the geosynthetic. The methodology is applied to four woven geotextiles of different weights. The results of the new calculation method yielded a better stress-strain correlation with direct tensile strength tests, presenting the smallest relative errors compared to the other indirect calculations reviewed. With the aid of a disk and pins, vertical displacement values at different points in the geotextiles were measured and showed good agreement with analytical predictions. Therefore, the static puncture test combined with the new proposed calculation method is a good alternative for determining the stress-strain parameters of geotextile. 相似文献
88.
In this paper we developed and tested an integrated methodology for assessing direct and indirect economic impacts of flooding. The methodology combines a spatial analysis of the damage to the physical stock with a general economic equilibrium approach using a regionally-calibrated (to Italy) version of a Computable General Equilibrium (CGE) global model. We applied the model to the 2000 Po river flood in Northern Italy. To account for the uncertainty in the induced effects on regional economies, we explored three disruption and two recovery scenarios. The results highlight that: i) the flood event produces indirect losses in the national economic system, which are a significant share of the direct losses, and ii) the methodology is able to capture both positive and negative economic effects of the disaster in different areas of the same country. The assessment of indirect impacts, in particular, is essential for a full understanding of the economic outcomes of natural disasters. 相似文献
89.
Zeming Gu Qi Wang Xiaoqin Sun Lingwei Lu Yuwei Zhang Ran Wang Shu Jin Yinlin Shao Jun Qian Xiaoxiang Xu 《材料科学技术学报》2021,87(28):46-53
P-type semiconductivity has been observed in solid solution series (SrTiO3)1-x(CaCr0.5Nb0.5O3)x (0.0 ≤x ≤ 0.15),which all adopt cubic symmetry and own intense absorption in the visible light region.These solid solutions are superior H2 evolution photocatalysts under visible light illumination (λ ≥400 nm).An AQE as high as 1.02 % at 420 ± 20 nm has been achieved at optimal composition(SrTiO3)0.85(CaCr0.5Nb0.5O3)0.15 which significantly surpasses the parent compounds.Stoichiometric H2/O2 production under visible light illumination has been successfully realized using Z-scheme system containing (SrTiO3)0.85(CaCr0.5Nb0.5O3)0.15,WO3 and I-/IO3-redox couple. 相似文献
90.
Z-型光催化剂可以有效增强电荷分离, 从而改善光催化剂的活性。采用浸渍-煅烧和水热法两步制备Z型BiVO4/GO/g-C3N4光催化剂, 并用不同手段对其进行表征。在BiVO4/GO/g-C3N4的光催化过程中, GO纳米片作为BiVO4和g-C3N4之间的快速传输通道, 可以抑制电子-空穴复合, 显著促进电荷分离, 提高三元异质结的氧化还原能力。与单组分或二元复合物相比, 该催化剂具有良好的光降解罗丹明B(RhB)的能力。在可见光照射下, 它能够在120 min内降解85% RhB, 空穴(h+)在反应中起主要作用。该工作为三元光催化剂体系提供了简单的制备方法, 其中g-C3N4通过GO与BiVO4偶联, 光催化活性显著提高。 相似文献