Science Bulletin
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2023
·
IF 18.9
Guangxun Sun,Dongyuan Liu,Min Li,Shu Tao,Zekun Guan,Yanfei Chen,Shihuan Liu,Qingzhou Du,Han Guo,Xinyue Yuan,Xinying Zhang,Houyu Zhu,Bin Liu,Yuan Pan
Development of efficient catalysts with high atomic utilization and turnover frequency (TOF) for H 2 activation in slurry phase hydrocracking (SPHC) is crucial for the conversion of vacuum residue (VR). Herein, for the first time, we reported a robust and stable single atoms (SAs) Mo catalyst through a polymerization-pyrolysis- in situ sulfurization strategy for activating H 2 in SPHC of VR. An interesting atomic coordination structural dynamic evolution of Mo active sites was discovered. During hydrocracking of VR, the O atoms that coordinated with Mo were gradually replaced by S atoms, which led to the O/S exchange process. The coordination structure of the Mo SAs changed from pre-reaction Mo-O 3 S 1 to post-reaction Mo-O 1 S 3 coordination configurations, promoting the efficient homolytic cleavage activation of H 2 into H radical species effectively. The evolved Mo SAs catalyst exhibited robust catalytic hydrogenation activity with the per pass conversion of VR of 65 wt%, product yield of liquid oils of 93 wt%, coke content of only 0.63 wt%, TOF calculated for total metals up to 0.35 s −1 , and good cyclic stability. Theoretical calculation reveals that the significant variation of occupied Mo 4d states before and after H 2 interaction has a direct bearing on the dynamic evolution of Mo SAs catalyst structure. The lower d -band center of Mo-O 1 S 3 site indicates that atomic H diffusion is easy, which is conducive to catalytic hydrogenation. The finding of this study is of great significance to the development of high atom economy catalysts for the industrial application of heavy oil upgrading technology .
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Sustainable Energy & Fuels
·
2023
·Vol. 7
·期 4
·977-985
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IF 5.6
Tingting Wen,Limin Wang,Yaqiong Gong
Design and synthesis of a highly efficient OER catalyst is the key to improve the efficiency of hydroelectrolysis for hydrogen production. In this paper, a rational approach to improve the catalytic performance of CoMoO4 nanomaterial was reported. A nanoflower structured CoMoO4 precursor was synthesized on nickel foam using a typical hydrothermal method. Then, CoMoO4/NF was etched through brief immersion in iron nitrate solution at room temperature to produce FeOOH–CoMoO4/NF. The unique 3D structure of FeOOH–CoMoO4/NF could availably promote interfacial electron transfer as well as effectively provide abundant active sites, and it exhibited excellent electrocatalytic activity. FeOOH–CoMoO4/NF requires an overpotential of 209 mV to achieve a current density of 10 mA cm−2. Meanwhile, the material FeOOH–CoMoO4/NF exhibits excellent catalytic durability of up to 24 h, which is promising for practical applications in energy conversion. Thus, this work may offer a viable strategy to assemble remarkable OER electrocatalysts.
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2023
·
IF 6.1
Hongwei Ren,Hongyu Dong,Tengda Zhao,Zhongqing Yan,Benzhen Jia,Liang Han,Jinfeng Zhang
Activated carbon (AC) is one of the typical adsorbents for industrial treatment of VOCs, but AC itself has a high calorific value. When the heat generated by low-temperature oxidation cannot be released, it is easy to store heat and oxidize spontaneously, resulting in immeasurable harm. Therefore, it is important to study and improve the thermal stability of AC. In this study, Mo-doped carbon quantum dots (CQDs) was synthesized to enhance the safety of AC usage. The structure of AC before and after modification was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). On the modified Mo-doped CQDs/AC, there are more crystalline structures formed by Mo oxides on the surface, which makes the intermolecular force on the surface of AC increase. At the same time, Mo oxide has strong oxidation resistance, which can inhibit the thermal decomposition process of AC, and has stronger stability. The spontaneous combustion tendency and thermal hazard of AC before and after modification were greatly improved. The heat released in the toluene adsorption by the modified AC at different temperatures was significantly lower than the heat released by the unmodified AC. According to the Langmuir adsorption isotherm, the adsorption performance of Mo-doped CQDs (2.5 wt%) was 1.6 times higher than that of AC when the system was 25 °C. The results showed that Na 2 MoO 4 CQDs modified AC could effectively improve the thermal stability and greatly reduce the spontaneous combustion tendency. A relative fire safety performance evaluation model was also established to comprehensively evaluate the fire risk of VOCs treatment by AC.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Weiwei Han,Yang Qian,Fan Zhang,Yi He,Ping Li,Xingwang Zhang
The application of proton exchange membrane water electrolysis (PEMWE) is largely limited by the sluggish oxygen evolution reaction (OER) kinetics, which usually requires noble metal Ir/Ru-based catalysts. It’s desirable to design low-cost catalysts with less content of Ir/Ru in OER without sacrificing their catalytic performance. Herein, the ultrasmall IrO 2 nanoparticles uniformly dispersed on Co 3 O 4 -CoMoO 4 nanocages (IrO 2 @Co 3 O 4 -CoMoO 4 ) electrocatalyst is demonstrated. Structural characterization indicates that hollow Co 3 O 4 -CoMoO 4 acts as the effective support to provide abundant anchoring sites and heterogenous interfaces, which enable the catalyst to expose more active sites and accelerate charge transport. As a result, the representative IrO 2 @Co 3 O 4 -CoMoO 4 exhibits an outstanding OER activity ( η = 236 mV at 10 mA cm −2 ) with a superior mass activity of 713 A g –1 Ir at 1.53 V vs. RHE in 0.5 M H 2 SO 4 that are comparable to most reported catalysts. Theoretical calculations also reveal that the introduction of Mo can effectively modify electronic structure and decrease adsorption energy barriers of oxygen intermediates, and thereby enhancing OER catalytic activity. This work provides a new idea to develop highly efficient low Ir catalysts for OER.
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CHEMICAL PHYSICS LETTERS
·
2022
·
IF 2.719
Min Wang,Beiyang Guo,Jiayu Zhan,Yuan Zhuang,Sridhar Komarneni,Jianfeng Ma
Mo-doped BiOBr nanoflowers were prepared by hydrothermal method with various Bi:Mo molar ratios, and their degradation efficiency of tetracycline under visible light was investigated using K 2 S 2 O 8 activation. Among the above series of catalysts, the sample containing 2% Mo dopant exhibited the optimum photocatalytic activity, which could efficiently remove tetracycline (TC) within 40 min. The mechanism of photocatalytic activity can be well explained by the generation of superoxide radicals (O 2 − ), sulfate radicals (SO 4 − ), hydroxyl radicals ( OH) and holes (h + ), which are responsible for the degradation of TC. In addition, the 2 %Mo-BiOBr catalyst has good recycling stability.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Sensen Yu,Yongjin Zou,Qingyong Wang,Jie Xu,Cuili Xiang,Fen Xu,Lixian Sun,Fan Yang
The development of high-efficiency and cheap electrocatalysts for hydrogen evolution reactions (HER) is of great importance for the electrochemical production of hydrogen. In this study, self-supported CoMoS on carbon nanofiber (CoMoS@CNF) catalysts were prepared through a one-step hydrothermal method using carbonized, electrospun polyacrylonitrile–dopamine (DA) polymeric fibers. The –OH group on DA was utilized to immobilize 1,2,3,4-Butanetetracarboxylic acid on the surface of the modified fiber, which consequently captured Co and Mo ions . Self-supported CoMoS nanosheet and nanosphere clusters grew on the surface of the CNF. The core–shell and layered nanosheet stacked structures created abundant accessible active sites, convenient ion diffusion pathways, and opened channels for the rapid release of the evolved H 2 . Density functional theory calculations showed that the heterojunctions constructed from CoS 2 and Mo 2 S 3 had low free energies for the adsorption of hydrogen. The prepared CoMoS@CNF electrode required a low overpotential (105.2 mV) to reach 10 mV cm −2 in 1 M KOH and showed no deterioration in the electrochemical performance even after 20 h of continuous operation at a 10 mV overpotential. The excellent activity and stability of the self-supported CoMoS@CNF electrocatalysts toward HER in alkaline medium is possibly due to its advantageous electronic and geometrical structure.
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CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Zhiyuan Ma,Huichao Cheng,Jinglian Fan,Zhenwei Wang,Zhanggen Liu
In this study, to improve the fracture toughness of Si 3 N 4 ceramics and overcome the reduction in the hardness caused by toughening, the Si 3 N 4 -based composite ceramics were prepared by spark plasma sintering . Fixed amounts of Y 2 O 3 (7 wt%) and TiC (8 wt%) together with Mo adjusted in the range of 0-8 wt% were incorporated into the Si 3 N 4 matrix. Besides, Si 3 N 4 composites were also prepared as control groups by excluding TiC and Mo. The results reveal that the addition of TiC improves the hardness of the Si 3 N 4 composites by inhibiting the transformation from α-Si 3 N 4 to β-Si 3 N 4 and grain refinement. Meanwhile, the high hardness of the composites is maintained even after toughening with Mo. The addition of Mo promotes the nucleation and phase transformation of α-Si 3 N 4 by promoting the transfer of the Si and N atoms. At the same time, molybdenum silicide is formed in-situ, improving fracture toughness through various toughening mechanisms. The Si 3 N 4 composites with 8 wt% TiC and 8 wt% Mo sintered at 1700 °C exhibit the optimal properties, with Vickers hardness and fracture toughness determined to be 18.25 GPa and 10.2 MPa•m 1/2 , respectively.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
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IF 8.6
Jiayu Li,Jun Xiong,Haoxue Huang,Mei Zhang,Wenshuai Zhu,Jun Di
The non-stoichiometric structure of tungsten oxide (W 18 O 49 ) makes it easy to form oxygen vacancies near the low-valence W atoms, so the W 18 O 49 can be applied to oxidative desulfurization. To further improve the desulfurization activity of W 18 O 49 to meet the increasingly stringent environmental requirements, Mo doping and plasma-induced surface reconstruction cooperative strategies are developed. The incorporation of Mo species into the W 18 O 49 surface by replacing W sites can adjust the atomic and electronic structure of the catalyst surface and form more oxygen vacancies. After Mo doping into the W 18 O 49 , the plasma bombarded the surface of material to destroy part of the surface structure, thus producing the reactive sites with low coordination numbers. This reconstructed atomic surface also accompany to generate more oxygen vacancies, thus greatly improving the catalytic activity. Compared to pure W 18 O 49 , significantly improves oxidative desulfurization performance can be achieved over Mo-W 18 O 49 -P, and deep desulfurization is realized within 3 h. Moreover, the optimal Mo-W 18 O 49 -P shows better stability than pure W 18 O 49 , which can be recycled for 12 times. This work provides an accessible pathway for cooperative enhancing the catalytic oxidative desulfurization activity of oxide catalysts.
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ChemSusChem
·
2023
·Vol. 16
·期 17
·e202300633
·
IF 8.4
Wen Guo,Tao Yang,Hongyan Zhang,Hao Zhou,Maoshuai He,Wenxian Wei,Wenjie Liang,Yilin Zhou,Tingting Yu,Hong Zhao
Graphical A thick Ni-based catalyst layer derived from nickel foam was synthesized by a Fe 3+ -induced strategy. In addition to the remarkable conductivity, high stability and more accessible active sites, Mo,Fe co-modulation also optimizes the adsorption free energies of the OER intermediates, boosting the catalytic activities. A highly active catalyst for the oxygen evolution reaction (OER) is critical to achieve high efficiency in hydrogen generation from water splitting. Direct conversion of nickel foam (NF) into nickel-based catalysts has attracted intensive interest due to the tight interaction of the catalysts to the substrate surface. However, the catalytic performances are still far below expectation because of the problems of low catalyst amount, thin catalyst layer, and small active area caused by the limitations of the synthesis method. Herein, we develop a Fe 3+ -induced synthesis strategy to transform the NF surface into a thicker catalyst layer. In addition to the excellent conductivity and high stability, the as-prepared FeMo-Ni 2 P 2 O 7 /NF catalysts expose more active sites and facilitate mass transfer due to their thicker catalyst layer and highly dense coral-like micro-nano structure. Furthermore, the Mo, Fe co-modulation optimizes the adsorption free energies of the OER intermediates, boosting catalytic activities. Its catalytic activity is among the highest, and it exhibits a small Tafel slope of 34.71 mV dec −1 and a low overpotential of 161 mV for delivering a current density of 100 mA cm −2 compared to reported Ni-based catalysts. The present strategy can be further used in the design of other catalysts for energy storage and conversion.
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ChemNanoMat
·
2023
·Vol. 9
·期 7
·e202300087
·
IF 3.8
Tingyi Wu,Huanglin Dou,Zhenxin Zhao,Junliang Zhou,Xiaomin Wang
Graphical The NiMoO 4 -modified separator can not only use its own strong polarity to chemisorption of polysulfides and effectively suppress the shuttle effect, but also can promote the mutual transformation between polysulfides of different phases, reduces the reaction potential barrier, and the redox kinetics is significantly improved. Besides, the hollow microsphere structure facilitates the penetration of electrolyte and establishes a pathway for ion/electron transport, which accelerates the Li + diffusion rate. Lithium-sulfur (Li−S) batteries are considered to be the most promising candidates for achieving low-cost, high-energy density systems. The serious shuttle effect of polysulfides (LiPS) and the sluggish redox kinetics have become major obstacles to the practical application of Li−S batteries. Herein, a hollow microsphere structure of transition bimetallic oxide nickel molybdate (NiMoO 4 ) was prepared by hydrothermal reaction and calcination method. It was used as a separator coating material to inhibit LiPS shuttle and promote efficient redox conversion of sulfur species. The hollow microsphere structure not only possesses a large internal space to physically confine LiPS but also exposes abundant active sites to enhance the redox kinetics of LiPS. The NiMoO 4 shows superior adsorption ability for LiPS and accelerated ion/electron transport rates compared to NiO, thus facilitating the anchoring-conversion-diffusion processes of polysulfides. Benefiting from this versatility, the Li−S batteries with NiMoO 4 -PP exhibit a high discharge specific capacity of 1354.5 mAh g −1 at 0.1 C. In addition, the battery exhibits excellent cycling stability with a capacity decay rate of 0.027% for 500 cycles at 2 C. These results demonstrate the potential application of NiMoO 4 -based electrocatalysts in high-performance Li−S batteries.
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RSC Advances
·
2021
·Vol. 11
·期 60
·37932-37941
·
IF 3.361
Ge Guo,Wenzhi Li,Tauseef Ahmed,DuoDuo Hu,Ru Cui,Baikai Zhang,Xia Zhang
Non-noble bimetallic NiMo supported on zeolitic imidazolate framework-derived porous carbon (NiMo@FDC) catalyst for lignin depolymerization has been successfully developed. The synergism between Ni and Mo species in NiMo@FDC catalyst could promote the catalytic cleavage of C–O linkages in Kraft lignin. At a low reaction temperature of 240 °C and under 4 MPa H2, the lignin liquefaction yield was 98.85 wt% and minimum coke yield was 1 wt%, particularly when using 10%NiMo@FDC catalyst. Additionally, at a high reaction temperature of 300 °C and under 2 MPa H2, there was an overall yield of 86 wt% of liquid product and 42 wt% of petroleum ether soluble product. The higher heating value (HHV) increased from 27.65 MJ kg−1 to 34.11 MJ kg−1. In the cycling experiment, the bifunctional catalyst also demonstrated reversability and stability. The synergy of Ni hydrogenation sites and Mo coupled adsorption sites identified a possible mechanism path, which could offer considerable potential for lignin depolymerization.
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Chemistry-An Asian Journal
·
2023
·Vol. 19
·期 2
·e202300951
·
IF 4.1
Pengkun Xia,Jing Pan,Yue Zhang,Mingzhen Mao,Lei Ma,Jianlin Chen,Long Zhang,Hui Wang,Hui Fan,Xiaohui Gao,Lianwen Deng
Graphical Mo−CoO nanosheets grown on nickel foam was used as a non-enzymatic glucose sensing electrode with a high sensitivity (89.3 mA cm −2 mM −1 ) and a low detection limit (0.43 μM). DFT calculations results confirmed that the lower adsorption free energy (−1.79 eV) for glucose adsorbing on Mo−CoO-1 surface promoted the glucose electrochemical oxidation reaction and then enhanced the sensing performance. In this work, a Mo doped CoO nanosheet grown on nickel foam (labeled as: Mo−CoO) with defect-rich and improved electron transfer capacity was designed to be used as a novel non-enzyme electrode material. Physical characterizations demonstrated the Mo elements were doped inside of the samples and they were mutually stabilized with each other, resulting in a high structural stability electrochemical catalytical activity even if the content of Mo was low. For non-enzymatic glucose electrochemical sensing, the prepared Mo−CoO-1 showed a remarkable sensitivity of 89.3 mA cm −2 mM −1 , and a low detection limit of 0.43 μM. Density functional theory (DFT) studies revealed that the doped Mo atom exhibited a higher d-band center compared to the Co atom. A stronger p-d orbital hybridization between the glucose and the Mo atoms indicated the enhancement of glucose adsorption and activation. Importantly, Mo−CoO-1 provided a good selectivity and long-term stability, which can be expected to be used in future practical applications.
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