Catalysis Science & Technology
·
2022
·Vol. 12
·期 15
·4817-4825
·
IF 6.177
Shilin Kang,Zhijun Li,Zhikun Xu,Ziqing Zhang,Jianhui Sun,Ji Bian,Linlu Bai,Yang Qu,Liqiang Jing
Although g-C3N4-based heterojunctions show promise for photocatalytic CO2 reduction, enhancing charge separation and creating sufficient catalytic sites remain challenges. In this study, mixed-valence CuPc/graphene/g-C3N4 (HT-CuPc/G/UCN) ultrathin heterojunctions (∼4.8 nm thickness) with Cu1+/Cu2+ species were constructed by H-bond induced assembly and subsequent post-treatment with H2. The optimized H100-CuPc/G/UCN sample showed 36-times higher activity than bare ultrathin g-C3N4 (UCN) for photocatalytic CO2 reduction to CO. Based on atomic force microscopy images, normalized photocurrent action spectra, electron paramagnetic resonances, and in situ diffuse reflectance infrared Fourier transform spectra, it was confirmed that the unexpected photocatalytic activity of H100-CuPc/G/UCN was attributed to the dual-functional roles of the introduced graphene: to increase the optimized amount of CuPc and enhance the high-level-energy electrons transferring from UCN to CuPc and the created Cu1+/Cu2+ species by H2 reduction as active catalytic sites for CO2 reduction. This work provides a comprehensively feasible strategy for preparing rational heterojunctions toward high-efficiency solar-driven CO2 reduction.
研究领域:
材料科学
·
环境科学
·
化学
✓ 已验证
DOI
高影响因子
Nanomaterials
·
2025
·Vol. 15
·期 11
·806
·
IF 4.3
Xiaojiao Yang,Shuai Han,Hongna Xing,Yi Dong,Xia Deng,Yan Zong,Juan Feng,Xiuhong Zhu,Xinghua Li,Xinliang Zheng
MOFs-derived magnetic carbon-based composites are considered to be valuable materials for the design of high-performance microwave absorbents. Regulating phase structures and introducing mixed-valence states within the composites is a promising strategy to enhance their charge transfer properties, resulting in improved microwave absorption performance. In this study, iron oxide components show a temperature-dependent phase evolution process (α-Fe 2 O 3 →Fe 3 O 4 →Fe 3 O 4 /FeO), during which the valence states of iron ions are regulated. The tunable phases modulate the magnetic Fe 3 O 4 component, resulting in enhanced magnetic loss. The changed valence states affect the polarization relaxation by adjusting the electronic structure and tune the electron scattering by introducing defects, leading to enhanced dielectric loss. The microwave absorption properties of iron oxide@carbon composites display phase- and valence state-dependent characteristics. Especially, Fe 3 O 4 @C composites exhibit superior microwave absorption properties, ascribed to the improved magnetic/dielectric losses induced by good impedance matching and strong microwave attenuation capacity. The minimum reflection loss of Fe 3 O 4 @C composites reaches −73.14 dB at 10.35 GHz with an effective absorption bandwidth of 4.9 GHz (7.69–12.59 GHz) when the absorber thickness is 2.31 mm. This work provides new insights into the adjustment of electromagnetic parameters and microwave absorption properties by regulating the phase and valence state.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2025
·
IF 8.3
Lingwei Yu,Leyi Zhou,Qi Guo,Hongchuan Zhang,Xi Xiao,Ruixue Zhao,Zifeng Yan,Ying Zhang
The challenge of converting carbon dioxide (CO 2 ) electroreduction into high value-added products is to obtain highly selective electrocatalysts. Research has shown that cuprous oxide (Cu 2 O) effectively facilitates the activation of CO 2 and suppress the competing hydrogen evolution reaction. However, during the process of electrochemical reduction, the valence state of Cu 2 O is prone to transformation. Herein, a series of Cu 2 O–CeO 2 -X catalysts (X represents different amounts of CeO 2 added) by applying Cu 2 O onto Cerium oxide (CeO 2 ) nanorods were synthesized via the impregnation method and used as electrocatalysts. We found that the Faradaic efficiency of methane (FE-CH 4 ) for Cu 2 O–CeO 2 -2 reached 65.1 % at −1.6 V vs. RHE, exceeding many catalysts previously reported. From the Cu LMM Auger spectra, it was found that the valence state of Cu species in Cu 2 O–CeO 2 -2 is mainly Cu 0 (accounting for 93.39 %), while in Cu 2 O–CeO 2 -3, the proportion of Cu 0 is 56.34 %. This indicates that CeO 2 has a regulatory effect on the valence state of Cu species. Additionally, we observed the valence state of Cu in Cu 2 O–CeO 2 -2 after the CO 2 reduction reaction and found that the proportion of Cu 0 changed little (94.97 %), which proves that CeO 2 plays a role in stabilizing the valence state of Cu. Research has demonstrated that Cu 0 can adsorb the ∗CO intermediate on its surface, followed by a hydrogenation reaction to generate CH 4 (∗CO + H + + e − → ∗CHO). Copper-based catalysts in which Cu 0 dominates among the Cu species are conducive to the conversion of CO 2 into CH 4 . In situ ATR-SEIRAS spectra confirmed the presence of key intermediates such as ∗CHO and explored the formation pathway of CH 4 (CO 2 → ∗COOH → ∗CO → ∗CHO → ∗OCH 2 → CH 4 ). This study provides a new way to design efficient copper oxide-based catalysts for CO 2 electroreduction by adjusting and stabilizing the ratio of copper valence state reasonably.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Hao Qu,Sihui He,Yue Su,Yulong Zhang,Haiquan Su
Direct synthesis of ethanol from syngas (a mixture of H 2 and CO) is considered as an eco-friendly and industrially important process to produce renewable fuels and chemicals. The current non-noble metal catalyst systems suffer from either low selectivity or multiple processes with high energy consumption. Here, we report a novel molybdenum diselenide-based catalyst system for high-selective conversion of syngas into ethanol. For a series of K-promoted MoSe 2 catalysts with different K/Mo ratios (K x -MoSe 2 , x = 0.25-1.00), K 1.00 -MoSe 2 surprisingly exhibits excellent ethanol selectivity up to 58.7 C mol % in total alcohols and 31.1 C mol % in the total product, which is higher than the highest selectivity value for the non-noble metal catalysts reported in the literature. The high ethanol selectivity is attributed to the formation of K-Mo-Se active phase and the synergistic effect of the Mo IV , Mo V and Mo VI multivalent species in the active phase. This study opens up a highly selective non-noble metal catalyst system for the direct synthesis of ethanol by syngas, which is of practical significance for the catalytic conversion of hydrogen-poor syngas.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Meng Zhang,Xuezhang Xiao,Zhouming Hang,Man Chen,Xuancheng Wang,Nan Zhang,Lixin Chen
Magnesium hydride, as a potential solid state hydrogen carrier has attracted great attention around the world especially in the energy storage domain due to the high hydrogen storage capacity and the good cycling stability. But kinetic and thermodynamic barriers also impede the practical application and development of MgH 2 . Nanoscale catalysts are deemed to be the most effective measure to overcome the kinetic barrier and lower the temperature required for hydrogen release in MgH 2 . NbN nanoparticles (~20 nm) with intrinsic Nb 3+ -N and Nb 5+ -N were prepared using the molten salt method and used as catalysts in the MgH 2 system. It is found that the NbN nanoparticles exhibit a superior catalytic effect on de/rehydrogenation kinetics for the MgH 2 /Mg system. About 6.0 wt% hydrogen can be liberated for the MgH 2 +5NbN sample within 5 min at 300 °C, and it takes 12 min to desorb the same amount of hydrogen at 275 °C. Meanwhile, the MgH 2 +5NbN sample can absorb 6.0 wt% hydrogen within 16 min at 150 °C, and absorb 5.0 wt% hydrogen within 24 min even at 100 °C. Particularly, the catalyzed samples exhibit excellent hydrogen absorption/desorption kinetic stability. After multiple cycles, there is no kinetic attenuation and the hydrogen capacity remains at about 6.0 wt%. It is demonstrated that the NbN nanoparticles with intrinsic multiple valence can be the critical effect in improving the hydrogen storage kinetics of MgH 2 . The stability of Nb 4 N 3 phase and Nb 3+ -N and Nb 5+ -N valence states can ensure a stable catalytic effect in the system.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2018
·
IF 2.524
Weimin Li,Faqin Dong,Liang Bian,Hao Zou,Mianxin Song
In this study, Ce-doped zirconolite was synthesized through high-temperature solid-state reaction at 1250 °C in air for 96 h. The crystal phase, microstructure and valence transition were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Phase relations of CaZr 1– x Ce x Ti 2 O 7 systems were determined by XRD analyses and Rietveld refinements . Four different phases are identified, namely zirconolite, perovskite , pyrochlore, and cerianite. The phase transformation (2M-zirconolite → 4M-zirconolite → Ce-pyrochlore) is caused by cations rearrangement as cerium content increases. The solubility limit of cerium ions in CaZr 1– x Ce x Ti 2 O 7 system is estimated to be approximately 0.80. Under sintering air atmosphere, partial reduction of Ce 4+ in Ce 3+ is detected in Ce 3d XPS spectra, and the ratio of Ce 3+ and Ce 4+ significantly decreases as cerium content increases.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2025
·
IF 3.5
Shengming Liu,Yun Zhang,Shihua Ding,Tianxiu Song
V cation was introduced at Nb-site in CoTiNb 2 O 8 for the purpose of tuning the defects concentration. XRD analysis indicated that no secondary phase developed over the whole composition range. The sintering temperature decreased to 1150 °C in current work, compared with pure CoTiNb 2 O 8 ceramic (∼1250 °C). V-introduction inhibited grain growth and benefited grain homogenization. The decreased molecular dielectric polarizability and blue shift of Raman A 1g mode both made lower ε r from 59.2 to 41.8. Based on the X-ray photoelectron spectroscopy (XPS), V doping decreased the oxygen vacancy concentration and tuned the Co valence state. The defects compensation by oxygen and Co vacancies significantly improved Q × f up to 38,012 GHz, accompanied with a 50% rise. The slight increase in τ f was attributed to the Nb-O bond energy reduction. The CoTi(Nb 0.97 V 0.03 ) 2 O 8 had a high ε r of 54.6 with good Q × f of about 38,012 GHz and τ f =96.47 ppm/°C. Enhanced Q × f and low sintering temperature were achieved simultaneously.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
INORGANICA CHIMICA ACTA
·
2022
·
IF 3.118
Jing-Wen Zhang,Ling-Xiao Wang,Xun Cheng,Lin-Lin Hou,Jing-Zhe Li,Chun-Feng Wang,Xiao-Wei Yan,Kuan-Guan Liu
To prepare new series of mixed-valence polynuclear Cu(I/II) clusters, chloride ions are introduced to construct two mixed-valence polynuclear Cu(I/II) clusters for evaluating their photothermal conversion performance. X-ray single-crystal structural analysis reveals their molecular formula are {Cu II [Cu I (Cy 3 P)] 4 (BTA) 4 Cl 2 }·5DMF (I·5DMF, Cy 3 P = triscyclohexylphosphine, BTA = benzotriazole, DMF = N, N -Dimethylformamide) and {(Cu II ) 3 [Cu I (PPh 2 Py)] 6 (BTA) 8 Cl 4 }·6DMF (II· 6 DMF, Ph 2 PyP = diphenyl-2-pyridylphosphine), respectively. X-ray Photoelectron Spectroscopy (XPS) and Electrospray Ionization Mass Spectrometry (ESI-MS) confirm their chemical composition and charge state. The reported two mixed-valence Cu I /Cu II clusters have different nucleus (penta-nucleus for I and nano-nucleus for II) and different proportion of valence state (1/4 for I vs 1/2 for II). The thermogravimetric analysis (TGA) reveals the thermal stability of both clusters is less than our previously reported penta-nucleus mixed-valence Cu I /Cu II clusters. Contrastively studies of their optical absorption properties by the solid-state ultraviolet diffuse reflection spectra indicate high-nucleus mixed-valence Cu I /Cu II cluster with higher proportion of Cu II is superior to those penta-nucleus mixed-valent Cu(I/II) clusters. With the introduction of chloride ions to the structures of mixed-valence Cu I /Cu II clusters have not remarkably changed their photothermal conversion performance. This study provides a practicable way to construct new mixed-valence Cu I /Cu II clusters with different photothermal conversion performance.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
ChemistrySelect
·
2022
·Vol. 7
·期 45
·e202203339
·
IF 2.307
Junjie Zhang,Zhourong Xiao,Li Wang,Xiangwen Zhang,Guozhu Li
Graphical The key role of Ni valence state on the catalytic SMR performance of Ni/Al 2 O 3 is reported. Ni 0 /Ni 2+ ratio on Ni/Al 2 O 3 is individually regulated by changing the reduction temperature while maintaining the states of nickel particles and support. A deep understanding is gained on how the Ni valence state of Ni/Al 2 O 3 affects the catalytic SMR performance. Steam methane reforming (SMR) is the most mature technology for hydrogen production in industry, and alumina supported nickel (Ni/Al 2 O 3 ) is the most widely used catalyst. Herein, the key role of Ni valence state on the catalytic SMR performance of Ni/Al 2 O 3 is reported. The ratio of Ni 0 /Ni 2+ on Ni/Al 2 O 3 is individually and effectively tuned by changing the reduction temperature after wet impregnation. Catalytic performance of Ni/Al 2 O 3 is greatly dependent on the surface concentration of Ni 0 and Ni 2+ . The catalyst reduced at 675 °C possesses balanced Ni 0 and Ni 2+ sites and exhibits superior catalytic performance, on which 60 % of methane is stably converted at 600 °C. CH 4 -TPD and CO-TPD profiles demonstrate that appropriate Ni 0 /Ni 2+ ratio can promote the adsorption of CH 4 and inhibit the moderate-strength adsorption of CO, which leads to increased SMR activity and selectivity.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jinxu Ma,Kepi Chen,Cuiwei Li,Xiaowen Zhang,Linan An
The valence-combination strategy was applied to design B-site substitution non-equimolar stoichiometric high-entropy perovskite oxides (HEPOs). 29, 56 and 29 valence combinations with the maximum configurational entropy higher than 1.5R for five-component HEPOs were identified when the average valence of B-site is 3, 4 and 5, respectively. Synthesis experiment was performed on 8 valence combinations with the average valence of B-site equal to 4. Single-phase HEPOs were obtained from 6 of them. It was also found that most of HEPOs have ordered structures. The formation of single-phase HEPO and ordered structure was discussed in terms of structural tolerance factor and valence-difference factor.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2022
·
IF 8.008
Qikun Zhang,Xiaoping Zhang,Yang Shu,Jianhua Wang
Copper is an essential element to play significant roles in human health associated to the strong redox properties of Cu(I) and Cu(II). The concurrent monitoring of copper species in biological matrixes is highly desired. Herein, a dual-channel fluorescence nanoprobe was designed for the speciation of mono- and divalent copper by conjugating carbon dots (CDs) with Eu-based metal–organic frameworks (Eu-MOFs). The obtained Eu-MOFs@CD nanoprobe exhibits fluorescence at λex/λem = 380/454 nm from CDs and λex/λem = 275/615 nm from Eu-MOFs. Bathocuproine disulfonate (BCS) specifically chelates Cu+ to produce a BCS–Cu+ adduct with absorption at 480 nm, which quenches the fluorescence of CDs at 454 nm due to the inner filter effect. On the other hand, Cu2+ quenches the fluorescence of Eu-MOFs due to the replacement of Eu3+ by Cu2+. Thus, Eu-MOFs@CDs enable extremely fast detection of Cu+ and Cu2+ within 1 min. Furthermore, the nanoprobe is demonstrated by monitoring the variation of Cu+ and Cu2+ in the degradation process of copper nanoparticles and Cu-based MOFs.
研究领域:
分析化学
·
生物医学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2020
·Vol. 22
·期 33
·18711-18721
·
IF 3.43
Linghui Zhang,Guoqiang Peng,Yujiang Wang,Tiejun Li,Dan Wang,Lili Han,Zhipeng Ci
The controllable design and precise modulation of the functional properties of materials based on theoretical calculations has always been the goal of materials researchers. Through the comparative analysis of theoretical calculations and experimental phenomena, physical properties, including optical properties, electrical conductivity, and dielectric properties, can be further comprehended. In this work, on the basis of the first-principles calculations of many inorganic compounds, we selected BaSnSi3O9 (BSSO) as the research focus and found that it contained two cationic sites with completely different electronic characteristics. Among them, the electron density of cations at the Ba site shows obvious localization characteristics, whereas the Sn site shows strong interaction with the surrounding environment. This distinct difference in electronic characteristics is very beneficial to the research and design of materials with functional properties. When functional ions are introduced into Ba sites, the relatively complete independence of these ions will be maintained. That is, if an ion with multiple stable valence states is introduced at the Ba site, it will exhibit the coexistence of multiple valence states. However, if an ion is introduced at the Sn site, this ion will lose its independence and exhibit strong interaction with the surrounding crystal field environment. The rare earth element europium (Eu) with two stable divalent and trivalent valence states in its normal state was chosen as a probe to verify the theoretical predictions in this work. According to the calculation results, when Eu occupied the Ba site, the spectrum simultaneously showed the luminescence of Eu3+ and Eu2+, and had a larger luminescence quenching concentration when the influence of defects was ignored. When Eu occupied the Sn lattice site, it only showed the luminescence of Eu3+, and had a lower luminescence quenching concentration due to the attractive effect that the surrounding O atoms had on the Eu electrons. Our research indicates that the experimental results are consistent with the theoretical predictions. This paper analyzes the important role of Eu optical probes in terms of investigating their physical mechanisms and optical properties in detail. It will provide valuable inspiration for theoretical calculations to guide the design of materials and the modulation of their functional properties.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）