Fe(III) grafted MoO3 nanorods for effective electrocatalytic fixation of atmospheric N2 to NH3

Electrocatalytic nitrogen reduction reaction (ENRR) offers a carbon-neutral process to fix nitrogen into ammonia, but its feasibility depends on the development of highly efficient electrocatalysts. Herein, we report that Fe ion grafted on MoO₃ nanorods synthesized by an impregnation technique can efficiently enhance the electron harvesting ability and the selectivity of H⁺ during the NRR process in neutral electrolyte. In 0.1 M Na₂SO₄ solution, the electrocatalyst exhibited a remarkable NRR activity with an NH₃ yield of 9.66 μg h^?1 mg^?1_cat and a Faradaic efficiency (FE) of 13.1%, far outperforming the ungrafted MnO₃. Density functional theory calculations revealed that the Fe sites are major activation centers along the alternating pathway.     

用于射频滤波器的LN单晶薄膜XBAR的性能研究

基于铌酸锂(LN)薄膜的横向激发体声波谐振器(XBAR)能够兼具大机电耦合系数(K²)和高谐振频率(f)特性，有望满足5G应用的频段要求。然而，常规LN薄膜单层XBAR结构的温度稳定性较差，频率温度系数(TCF)较低。该文提出一种具有SiO₂温度补偿层的SiO₂/LN双层结构XBAR，并建立了精确分析层状结构XBAR的有限元模型。理论分析表明，该双层结构XBAR上激励的主模式是一阶反对称(A1)兰姆波。通过合理优化结构参数配置，能够获得高谐振频率(f~4.75 GHz)和大机电耦合系数(K²~8%)，同时其温度稳定性也得到显著改善(TCF~-36.1×10^-6/℃)，相较于单层XBAR结构提高了近70×10^-6/℃，这为研制温补型高频、大带宽声学滤波器提供了理论基础。     

The role of carbon in microstructure evolution of SiBCO ceramics

The composition of polymer derived ceramics could be readily tuned through controlling the structure and element content of the polymer precursors, and investigation on the effect of the element on microstructure evolution is important to the design of advanced ceramics. In this article, the effect of carbon content in SiBCO polymer precursors was systematically investigated. The polymer network and thermal stability of polymer precursors and the carbon content of pyrolyzed SiBCO ceramic could be readily tuned by controlling the DVB amount used. Carbon contributed to the formation of graphitic carbon in SiBC_xO ceramics and inhibited the growth of β–SiC and SiO₂ crystals at 1600 °C, but lead to an increase in the graphitic carbon phase at 1800 °C.     

Increased hydroxyl concentration by tungsten oxide modified h-BN promoted catalytic performance in partial oxidation of methane

Hexagonal boron nitride (h-BN) as a layered inorganic nonmetallic material has been widely used. Hydrogen peroxide (H₂O₂) modification can trigger exfoliation and afford abundant B–OH active sites at edge of h-BN, which can enhance methane activation ability. Introducing tungsten oxide (WO₃) to h-BN produces a similar effect, because doping WO₃ into h-BN resulted in electron transfer to N, inducing fracture of B–N bond, resulting in N vacancy (triboron center), exposing more B sites and promoting the generation of B–OH. Significantly, the introduction of WO₃ on the modified h-BN dramatically increased the concentration of B–OH compared with the unmodified h-BN, because H₂O₂ modification weakened B–N bond. By means of XRD, TEM, XPS,EPR, FT-IR, it is proved that the high concentration of B–OH active sites contributed to activating C–H bond, thus methane conversion and CO and H₂ selectivity were significantly improved.     

Double emulsion (W/O/W) gel stabilised by polyglycerol polyricinoleate and calcium caseinate as mangiferin carrier: insights on formulation and stability properties

Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W₁/O/W₂ emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL⁻¹. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W₁/O/W₂ emulsions. Subsequently, the MGF-loaded W₁/O/W₂ emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W₁/O/W₂ emulsions were investigated. The MGF-loaded W₁/O/W₂ emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W₁/O/W₂ emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W₁/O/W₂ emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.     

滇黔相邻区二叠系宣威组富稀土黏土岩综合研究进展

在滇黔相邻区峨眉山玄武岩之上，二叠系宣威组下部广泛分布一套富稀土黏土岩。作为一种新类型的潜在稀土资源，诸多学者对其进行了研究，包括成矿条件、赋存状态，富集规律、综合利用方式等多个方面都有了较大的进展。该类型稀土具有非常大的资源潜力，区域连续性好、集中程度高，富含高价值的稀土元素镨、钕、铽、镝，经济价值和开发利用潜力巨大。本文全面总结了宣威组稀土目前的研究进展和存在的关键问题，提出了下一步研究方向。当前对于宣威组富稀土黏土岩中稀土元素的富集机理尚未明确，进一步开展成矿理论研究是找矿突破的关键；赋存状态的研究亟待突破，对该新类型稀土的综合利用技术突破，后期绿色勘查开发具有重要的意义；综合利用方面，经济可行的绿色选冶技术、伴生的铝、铌、锆、镓、钛等有价元素的综合回收、尾矿的资源化消纳等方面是下一步的主攻方向。      

Pristine and cobalt doped copper sulfide microsphere particles for seawater splitting

In this work, copper sulfide particles are synthesized with different Co doping concentrations such as 0, 1 and 5% at 80 °C by optimizing synthesis times from 1 to 3 h. Copper sulfide particles possess two structural phases of covellite CuS and digenite Cu₉S₅. The increase in synthesis time from 1 to 3 h increases the Cu₉S₅ phase growth and changes the morphology from flower to microsphere. The CuS synthesized with 0, 1 and 5% Co dopant concentrations demonstrate flower consisting of agglomerated nanosheets, microsphere and flower like microsphere. The elemental investigation substantiates Co ions presence in CuS microspheres. The A_1g (LO) mode intensity is decreased with increase in Co dopant concentration confirming Co incorporation into CuS microsphere. The CuS synthesized with 0, 1, 5% Co dopants exhibit 322 mV, 305 mV and 289 mV to attain 100 mA/cm² in 1 M KOH seawater. The CuS synthesized with 5% Co dopant demonstrates higher double layer capacitance (C_dl) of 173.9 mFcm^?2 and lower charge transfer resistance (R_ct) of 6.07 Ω with 78.84% retention after 10 h continuous stability than that of the other pristine (118.3 mFcm^?2, 13.72 Ω) and 1% Co doped CuS microsphere (165.7 mFcm^?2, 8.55 Ω) indicating more surface active site and rapid charge carrier transport, respectively.     

Catalytic behavior in CH4 decomposition of catalysts derived from red mud: Impact of residual Na2O

Catalyst samples for CH₄ decomposition were prepared from red mud (RM) by an acid-leaching neutralization precipitation approach. Water-washing the resultant precipitates multiple times, followed by drying at 105 °C and calcination at 500 °C, resulted in a threshold of residual Na₂O, equivalent to 96% Na₂O removal. Drying the precipitate at a higher temperature of 200 °C, followed by repeated water washing, provided a deeper Na₂O removal of 99% and made the resultant samples more active for the targeted reaction. Subsequently, four catalyst samples with a simulated red mud composition and NaOH contents from 0 to 0.3 wt% were prepared and the catalytic test results revealed that the Na₂O remaining in the RM-derived catalysts did not only inhibit their activation in CH₄ but also lower their maximal activities for CH₄ decomposition. Finally, two catalysts with the same simulated red mud composition and their Na impregnated respectively on Fe₂O₃ and a mixture support of Al₂O₃-SiO₂-TiO₂ were prepared and tested to explore the effect of Na distribution on the activation behavior of RM-derived catalysts for CH₄ decomposition. The activity testing results showed that it was the Na residual dispersed on iron oxides in the RM-derived samples to significantly inhibit the activation of CH₄ decomposition.