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1.
沈荣晨  郝磊  陈晴  郑巧清  张鹏  李鑫 《物理化学学报》2022,38(7):2110014-41
随着化石燃料使用的增加和温室气体排放量持续上升,20世纪以来气温上升得更快。开发环境友好型能源取代传统化石燃料是当务之急。氢能源作为一种清洁、高效的能源,被认为是最有希望取代传统化石燃料的能源。光催化水分解水产氢作为为一种环保型技术被认为是最有前景的氢能生产方法。提高光生电子-空穴对分离效率是构建高效光催化剂的关键。然而,利用高度分散的助催化剂构建高效、稳定的产氢光催化剂仍然是一个挑战。本文首次成功地采用一步原位高温磷化法制备了高度分散的非贵金属三金属过度金属磷化Co0.2Ni1.6Fe0.2P助催化剂(PCNS-CoNiFeP)掺杂P的石墨相氮化碳纳米片(PCNS)。有趣的是,PCNS-CoNiFeP与传统氢氧前驱体磷化法制备的CoNiFeP相比,没有聚集性,分散性高。X射线衍射(XRD)、X射线光电子能谱(XPS)、元素映射图像和高分辨率透射电镜(HRTEM)结果表明,PCNS-CoNiFeP已成功合成。紫外-可见吸收光谱结果表明,PCNS-CoNiFeP在200–800 nm波长范围内较PCNS略有增加。光致发光光谱、电化学阻抗谱(EIS)和光电流分析结果表明,CoNiFeP助催化剂能有效促进光生电子-空穴对的分离,加速载流子的迁移。线性扫描伏安法(LSV)结果还表明,负载CoNiFeP助催化剂可大大降低CNS的过电位。结果表明,以三乙醇胺溶液为牺牲剂的PCNS-CoNiFeP最大产氢速率为1200 μmol·h-1·g-1,是纯CNS-Pt (320 μmol·h-1·g-1)的4倍。在420 nm处的表观量子效率为1.4%。PCNS-CoNiFeP在光催化反应中也表现出良好的稳定性。透射电镜结果表明,6–8 nm的CoNiFeP高度分散在PCNS表面。高度分散的CoNiFeP比聚集的CoNiFeP具有更好的电荷分离能力和更高的电催化析氢活性。由此可见,聚合的CoNiFeP-PCNs (300 μmol·h-1·g-1)的产氢速率远低于PCNS-CoNiFeP。此外,CNS的P掺杂可以改善其电导率和电荷传输。  相似文献   
2.
The new design of the photocatalytic reactor is crucial to study for improving compatibility and scaling up the operation. A compatible loop photocatalytic reactor has been designed and used for rhodamine B decomposition. The photocatalysts were either ZnO or Fe-ZnO immobilized onto fiberglass cloth. The ZnO catalyst exhibited high crystallinity with or without Fe as the dopant. The crystallite size increased with the presence of Fe in the lattices. Most of the crystal parameters matched the standard ZnO data, and the cluster size was comparable to most reported studies. Diffuse Reflectance Spectroscopy (DRS) analysis confirmed the photon absorption shifted to the visible light range. The Fe dopant decreased the ZnO bandgap, and SEM-EDS confirmed the catalysts adhered to the fiberglass surface. The volume, thickness of the substrate solution, and reaction temperature influenced the photocatalytic-degradation rate. The photocatalytic degradation rate was higher under sunlight than ultraviolet irradiation. The reaction rate was lower in the batch reactor than in the loop reactor. The photocatalytic reaction almost completely mineralized RhB and changed the red solution to colorless. The immobilized photocatalyst has been reused more than 50 times without significantly decreasing the catalytic activity.  相似文献   
3.
Based on high specific surface area, high porosity of metal-organic frameworks (MOFs) and excellent visible light response of CdS, the CdS/Cd-MOF nanocomposites were constructed by in-situ sulfurization to form CdS using Cd-MOF as precursor and the CdS loading was controlled by the dose of thioacetamide. Under the irradiation of simulated sunlight, the degradation rate of methylene blue (MB) by 10 mg MOF/CdS-6 (mass ratio of MOF to thioacetamide is 6:1) was 91.9% in 100 min, which was higher than that of pure Cd-MOF (62.3%) and pure CdS (67.5%). This is attributed to the larger specific surface area of the composite catalysts, which provides more active sites. Meanwhile, the loading of CdS obviously broadens the light response range of Cd-MOF and improves the utilization of visible light. The Mott-Schottky model experiment shows that the formed type-II heterojunction between Cd-MOF and CdS can effectively inhibit the recombination of photogenerated electrons and holes. Meanwhile, the photocurrent intensity of MOF/CdS-6 is 8 times and 2.5 times of that of pure Cd-MOF and CdS. In addition, MOF/CdS-6 showed good photocatalytic performance after five cycles, showing excellent stability and reusability.  相似文献   
4.
Red mud wastes have been converted into mesoporous zeolite socony mobile-5 (ZSM-5) followed by deposited titanium dioxide (TiO2) nanoparticles to generate synergy adsorption-photodegradation for removal of dye removal in waste water. The amount of TiO2 loading was varied to achieve optimum photocatalytic activity while maintaining the mesoporosity and high surface area of ZSM-5. Sol-gel method facilitated the formation of anatase TiO2 on the ZSM-5. The fourier transform infrared spectra clarified the formation of Si–O–Ti at 957 cm?1 by the exchanging the hydrogen ion with titanium ion, which proved by decreasing the absorption band of Si–OH and Si–O interaction at 964 and 944 cm?1, respectively. Sol-gel method also preserved the mesopore diameter of ZSM-5 at 3.5 nm which allow the diffusion of methylene blue (MB) molecules into the pores. However, the surface area and the pore volume were slightly reduced with increasing the TiO2 loading. The adsorption performance of samples showed that the increasing in the TiO2 loading led to the decreasing in the adsorption capacity. All samples showed the suitability towards the pseudo second order kinetic. The Langmuir isotherm was suitable to describe the adsorption mechanism by monolayer adsorption. Mesoporosity of ZSM-5 accelerated the adsorption of dye via the increase of mass transfer in the pore channel which confirmed by the low intercept of intraparticle diffusion model at the first stage. The photocatalytic test showed that 10% TiO2 loading on the ZSM-5 exhibited the highest methylene blue removal followed by 5% and 20% TiO2 loading. Optimization on the amount of photocatalyst and the pH of solution indicated the reaction favoured 1 g L?1 of catalysts and at alkaline pH. 10% TiO2/ZSM-5 also exhibited high stability and reusability up to four reaction cycles. Photocatalytic performance of 10% TiO2/ZSM-5 was further investigated on photodegradation of malachite green and rhodamine B organic dyes, which showed the photocatalytic efficiency of 73 and 88%, respectively. Superoxide radical, hydroxyl radical, and photogenerated electron were identified as the main active species for MB photodegradation based on the reduction of degradation rate following the addition scavenger molecules.  相似文献   
5.
Photocatalytic CO2 reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution. Due to the environment-friendly, simple preparation, easy formation of highly-stable metal-nitrogen(M-Nx) coordination bonds, and suitable band structure, polymeric carbon nitride-based single-atom catalysts(C3N4-based SACs) are expected to become a potential for CO2 reduction under visible-light irradiation. In this review, we summarize the recent advancement on C3N4-based SACs for photocatalytic CO2 reduction to C1 products, including the reaction mechanism for photocatalytic CO2 reduction to C1 products, the structure and synthesis methods of C3N4-based SACs and their applications toward photocatalytic CO2 reduction reaction(CO2RR) for C1 production. The current challenges and future opportunities of C3N4-based SACs for photoreduction of CO2 are also discussed.  相似文献   
6.
曾彦  梁浩  管诗雪  王俊普  梁文嘉  黄梦阳  彭放 《中国物理 B》2022,31(1):16104-016104
Structural stability in terms of the decomposition temperature in LiMn2O4 was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn2O4 was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn2O4 varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn2O4 materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.  相似文献   
7.
This is the first of two articles(Part I and Part II)that presents the results of the new atomic mass evaluation,Ame2020.It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II.This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction,decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.All input data,including both the accepted and rejected ones,are tabulated and compared with the adjusted values obtained from the least-squares fit analysis.Differences with the previous Ame2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to Ame users.  相似文献   
8.
The reaction cross-sections of 124Xe(n, 2n)123Xe, 126Xe(n, 2n)125Xe, 128Xe(n, 2n)127Xe, 130Xe(n, 2n)129mXe, 132Xe(n, 2n)131mXe, 130Xe(n, p)130I, 131Xe(n, p)131I, and 132Xe(n, p)132I were measured at the 13.5, 13.8, 14.1, 14.4, and 14.8 MeV neutron energies. The monoenergetic neutrons were generated via the 3H(d,n)4He reaction at the China Academy of Engineering Physics using the K-400 Neutron Generator with a solid 3H-Ti target. A high-purity germanium detector was employed to measure the activities of the product. The reactions 93Nb(n, 2n)92mNb and 27Al(n, α)24Na were adopted for neutron flux calibration. The cross sections of the (n, 2n) and (n, p) reactions of the xenon isotopes were obtained within the 13–15 MeV neutron energy range. These cross-sections were then compared with the IAEA-exchange format (EXFOR) database-derived experimental data, together with the evaluation results of the CENDL-3, ENDF/B-VIII.0, JENDL-4.0, RUSFOND, and JEFF-3.3 data libraries, as well as the theoretical excitation function obtained using the TALYS-1.95 code. The cross-sections of the reactions (except for the 124Xe(n, 2n)123Xe and 132Xe(n, p)132I) at 13.5, 13.8, and 14.1 MeV are reported for the first time in this study. The obtained results are beneficial in providing better cross-section constraints for the reactions in the 13–15 MeV region, thus improving the quality of the corresponding database. Meanwhile, these data can also be used for the verification of relevant nuclear reaction model parameters.  相似文献   
9.
10.
对硫化镉反蛋白石结构光子晶体薄膜进行了可控合成,用巯基乙酸修饰的纳米晶和P(St-MMA-SPMAP)高分子小球共组装,成功地构筑了反蛋白石结构并用于可见光光解水产氢。结果表明,在可见光(λ≥420 nm)照射下,Cd S-310反蛋白石结构薄膜的光解水产氢性能比硫化镉纳米颗粒提高了一倍。这主要是因为等级孔结构反蛋白石光子晶体特性对催化剂的光催化性能的提升:首先,反蛋白石的周期性结构增加了光子在材料中的传播,提高了催化剂对太阳光的利用率;同时,大孔孔壁是由纳米颗粒堆积而成的,在反应中提供了更多的反应活性位点;此外,孔结构有利于物质的传输和分子的吸附。  相似文献   
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