对氧化石墨烯(GO)分别采用热还原(1200℃)和还原剂还原(水合肼)方法制备了两种还原氧化石墨烯(RGO)粉体.进而采用真空浸渍法,分别制备质量含量5％RGO,35％金属有机框架材料[MOF,MIL-101(Cr)-NH2]和60％石蜡(PW)的复合相变材料(CPCM).采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(FT-IR)和拉曼光谱对两种RGO的结构进行了考察,并用Hot Disk比较两种RGO对MOF基复合相变材料热导率的增强作用.结果表明:两种方法均有利于GO中含氧官能团的去除以及sp2杂化碳晶格有序度的变化,GO得到了有效还原.然而,负载两种RGO的金属有机框架材料基复合相变材料表现出了不同的导热性能.在常温下,MIL-101(Cr)-NH2和纯石蜡的热导率分别约为0.21W/(m·K)和0.25W/(m·K).加载5％还原剂法得到的RGO/MOF基复合相变材料的热导率值达到1.43W/(m·K),远远高于加载5％热还原法得到的RGO/MOF基复合相变材料的值[0.33W/(m·K)].因此,与低温热还原法相比,还原剂法对GO还原效果较好,在热管理用复合相变材料的导热增强方面更具有优势.

The low-usage of solar energy and the sluggish separation efficiency of the photogenerated electrons/holes pairs are the obstacles in the practical application of photocatalysts. The integration of upconversion and Z-scheme heterojunction is expected to break the barriers to achieve the efficient charge separation and broaden nearinfrared light absorption. Herein, an effective indirect Z scheme AgInS2/In2S3 heterostructure with carbon quantum dots (CQDs, as the electron conduction medium) and Lu3NbO7:Yb, Ho (as upconversion function) has been successfully synthesized. Consequently, the Lu3NbO7: Yb, Ho/CQDs/AgInS2/In2S3 heterostructure exhibited superior photocatalytic activities for Cr(VI) reduction and H2O2 production, reducing 99.9% of Cr(VI)(20 ppm, 15 min) and 78.5% of Cr(VI) (40 ppm, 30 min) with visible light irradiation as well as 94.0% of Cr(VI) (20 ppm, 39 min) under NIR light irradiation. Simultaneously, the heterostructure could generate 902.9 mu M H2O2 for 5 h under visible light irradiation. The intensive photocatalytic properties could primarily be attributed to the boosted light absorption capacity, the improved solar-to-energy conversion by the remarkable upconversion capacity of Lu3NbO7: Yb, Ho/CQDs and the faster charge transfer through a Z-schematic pathway. This work is anticipated to open a novel "window" for designing the efficient photocatalysts by coupling of Lu3NbO7: Yb, Ho and CQDs.

Background: The antibiotic and dyes disposals are the promising strategy for the persistent environmental problems. For the photocatalytic process, charge separation and transfer are the key issue, in which its rate should be faster than that of the recombination to participate into the chemical reactions. Methods: In this work, we exploited the Cu, Yb co-doped SnO2 via one-step hydrothermal method. The enhanced charge transfer rate was characterized by XPS, photocurrent, electrochemical impedance spectra, photoluminescence and EPR measurements. Significant findings: Benefiting from higher charge transfer rate, co-doping of Cu and Yb into SnO2 could achieve superior photocatalytic activities for the degradations of dyes and tetracycline. The result confirmed that the introductions of Cu and Yb could redistribute the photo-induced carriers on the surface of SnO2. In addition, the photogenerated electrons were captured by the defective sites, and thus it facilitated the efficient charge transfer over SnO2. (C) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

In order to address the leakage issue and enhance the thermal conductivity of phase change material (PCM), a composite carrier for shape-stabilized phase change material is developed for thermal energy management of battery. Metal organic framework (MOF): MIL-101-NH2, reduced graphene oxide (RGO), and paraffin wax (PW) were combined into a shape-stabilized CPCM to strengthen the heat transfer. MOF/RGO composite carrier was the heat transfer intensifier and the shape-stabilized container for PW. Here, the structural and thermal properties of CPCMs were evaluated by BET, SEM, XRD, FTIR, XPS, DSC, TGA and Hot Disk. The results show that MIL-101(Cr)-NH2/RGO/PW CPCMs were successfully prepared without any chemical reaction and the CPCM with mass fraction of PW of 60% has the best thermophysical properties. The melting enthalpy of the MOF(35%)/RGO(5%)/PW(60%) CPCM after 500 thermal cycles was calculated to be 80.55 J/g, which is close to its theoretical value. The thermal conductivity of the MOF(35%)/RGO(5%)/PW(60%) CPCM is increased by 472%, which is far higher than that of pure PW.

The construction of a phase junction photocatalyst can significantly enhance the photocatalytic performance with high selectivity for CO2 reduction. In this study, an S-scheme junction Cd0.5Zn0.5S/CoWO4 semiconductor with the coupling of a twin crystal Cd0.5Zn0.5S homojunction and CoWO4 was designed through a hydrothermal method, which could convert CO2 to CO with high efficiency under visible-light illumination. Cd0.5Zn0.5S-10%CoWO4 exhibited the optimal performance and its CO yield and selectivity were up to 318.68 μmol·g-1 and 95.90%, respectively, which were 4.54 and 1.62 times higher than that of twin crystal Cd0.5Zn0.5S. Moreover, the Cd0.5Zn0.5S homojunction with a zinc-blende and wurtzite phase and the S-scheme phase junction of Cd0.5Zn0.5S/CoWO4 enhanced the property of CO2 adsorption and accelerated the detachment of photogenerated carriers. The combination of photogenerated holes in Cd0.5Zn0.5S and the electrons of CoWO4 can retain the reduction sites to improve photocatalytic performance. This study provides a neoteric concept and reference for the construction of the S-scheme phase junction.

Sulfur vacancies can improve photocatalytic properties, which can be the center of the electrons-captured state to promote the separation and transfer of photogenerated carriers.

To effectively enhance the utilization of clean sunlight energy, harvesting a large percentage of near infrared (NIR) light is significant. One of the commonly used effective methods for modifying semiconductors is by co-doping upconversion materials on semiconductors to heighten the photocatalytic efficiency. In this work, Yb3+/Tm3+ co-doped InVO4 nanosheets were synthesized by a facile hydrothermal path, and the crystal phases, morphologies, surface chemical compositions, as well as optical properties were characterized. Yb3+/Tm3+ co-doped InVO4 revealed significantly enhanced photoactivity towards chromium(vi) reduction and methyl orange oxidation under visible or NIR light irradiation. Furthermore, 5YT-IV presented the highest electrocatalytic performance and photocatalytic production of H2O2 under visible light irradiation, requiring low overpotential and low Tafel slope (390 mV dec-1) for hydrogen evolution reaction than that of the bare InVO4 (731 mV dec-1), and as well improved the yield of photocatalytic H2O2 production by about 3.5 times. This was primarily ascribed to intensive light absorption resulting from the benign upconversion energy transfer of Yb3+/Tm3+ and the boosted charge separation caused by the intermediate energy states. Moreover, the presence of h+ and ˙O2- as the main oxidative species played a significant role during the photocatalytic oxidation process of methyl orange and electrons played a decisive role in Cr(vi) reduction. This study provides a promising platform for efficiently utilizing the visible-NIR energy of sunlight in the field of photocatalytic H2O2 production and for alleviating environmental pollution in future.