High-rate Decoupled Water Electrolysis System Integrated with α-MoO3 as a Redox Mediator with Fast Anhydrous Proton Kinetics

Hydrogen is a promising alternative to fossil fuels that can reduce greenhouse gas emissions. Decoupled water electrolysis system using a reversible proton storage redox mediator, where the oxygen evolution reaction and hydrogen evolution reaction are separated in time and space, is an effective approach to producing hydrogen gas with high purity, high flexibility, and low cost. To realize fast hydrogen production in such a system, a redox mediator capable of releasing protons rapidly is required. Herein, α-MoO₃, with an ultrafast proton transfer property that can be explained by a dense hydrogen bond network in the lattice oxygen arrays of HxMoO₃, is examined as a high-rate redox mediator for fast hydrogen production in acidic electrolytes. The α-MoO₃ redox mediator shows both a large capacity of 204 mAh g⁻¹ and fast hydrogen production at a current rate of 10 A cm⁻²(≈153 A g⁻¹), outperforming most of the previously reported solid-state redox mediators.     

碱性淀粉酶菌株的紫外线和He-Ne激光复合诱变及其产酶条件的研究

以嗜碱芽胞杆菌BC -A3 6为出发菌株,通过紫外线(UV)、亚硝基胍(NTG)及激光复合诱变处理,选育出一株目前高产碱性淀粉酶的突变株JG -5 7,在摇瓶发酵培养基上3 5℃培养45h ,测得酶活力稳定在867u/ml左右,为出发菌株酶活力的2 .1倍。该菌株产酶适宜的pH值为9-10。     

Pd-Ru/C催化剂的制备及其甲酸氧化活性研究

利用微波辅助有机溶胶法成功制备了Pd3Ru/C纳米电催化剂。相比传统的高压有机溶胶法,该法大大降低了有机溶剂的使用量并缩减了反应时间,是一种环境友好和资源节约的新型方法。采用XRD,TEM,XPS和电化学测试等手段对其结构和电化学性能进行了表征和评价。XRD和TEM结果表明微波辅助制备的Pd3Ru/C催化剂其粒径只有约3.0 nm,分散性也较Pd/C得到显著改善;XPS谱图证实催化剂活性组分Pd和Ru的原子比约为3.13∶1,Pd和Ru两种元素间发生了相互作用。与同条件制备的Pd/C催化剂相比,Pd3Ru/C催化剂在电极上发生甲酸氧化反应的主要峰电位负移了约100 mV,峰电流密度增大了2/3左右,其甲酸电氧化活性得到明显提高。     

Multi-Stage Porous Nickel–Iron Oxide Electrode for High Current Alkaline Water Electrolysis

Alkaline water electrolysis (AWE) is the promising technical pathway of large-scale green hydrogen production. The sluggish oxygen evolution reaction seriously hampers the water decomposition reaction kinetics for AWE, especially at high current density above 500 mA cm⁻². It is closely related with bubbles removal dynamic performance of porous electrodes. In this study, the multi-stage porous nickel–iron oxide electrode is prepared by a two-step electro-deposition method. The electrode shows good oxygen evolution reaction performance at high current densitiy of 1000 mA cm⁻², which is attributed to both the good electro-catalytic performance of NiFeO_x with nano-cone structure and good bubbles removal performance of porous Ni interlayer with the curved pore channels. Bubbles motion inside the pore channels is deeply analyzed by Lattice Boltzmann simulation of gas–liquid two-phase flows, combining with the experiments. The results indicate that bubbles motion speed is faster in curved pore channels than that in straight pore channels due to the role of bubble buoyancy. It illuminates the effects of pore channel curvature on bubbles motion for porous electrodes prepared by electro-deposition. It provides the possibility of designing porous electrodes with both good electro-catalytic performance and good bubbles removal performance by the electro-deposition method, from the view of industrial applications.     

800~1160 K下钢的氧化特性对发射率的影响

发射率是一项重要的表征物体表面辐射特性的热物性参数,与温度、测量波长、表面氧化、表面粗糙度等多种因素相关,研究其变化特征对红外测量有着重要意义。本文研究了在大气条件下,温度为800~1160 K范围内,测量波长为1.5 μm,带宽20 nm,钢SPHC样品的氧化特性对光谱发射率的影响。实验中每隔40 K为一个温度测量点,样品达到测量温度,持续加热3 h以上,每隔5 min记录一次光谱发射率的值。实验结果表明:①在相对低温阶段800 K、840 K铁与氧气生成三氧化二铁,该温度下氧化膜的增长主要来自这一反应过程;②在960 K左右三氧化二铁与铁反应生成氧化亚铁,这一阶段在测量温度下缓慢进行,需要较长时间样品表面光谱发射率才趋于稳定;③在1120 K以上,光谱发射率基本保持不变,样品表面氧化亚铁氧化膜快速形成。另一方面,我们拟合了在相同的加热时间里,温度对光谱发射率的影响,得出不同加热时间下温度与发射率之间的关系模型与实际模型之间描述非常准确一致。最后,实际应用中,在测量钢铁的温度时,应充分考虑由于空气中表面氧化对光谱发射率带来的影响。     

Ultrafine Homologous Ni2P–Co2P Heterostructures via Space-Confined Topological Transformation for Superior Urea Electrolysis

Constructing effective electrocatalysts based on ultrafine heterostructures is a promising strategy for boosting catalytic performance by exposing active sites and increasing specific surface area. However, the fabrication of catalytically active heterostructures with elaborate architectures is still poorly developed owing to synthetic challenges, and the intrinsic mechanism of heterogeneous interfaces remains unclear because of insufficient evidence regarding real active sites. In this study, ultrafine homologous Ni₂P–Co₂P heterostructures (Ni₂P–Co₂P/C) are created using a topological transformation strategy from a Ni–Co layered double hydroxide/carbon (Ni–Co LDH/C) interconnected structure in a single nanosheet. When employed as catalysts in urea oxidation reaction (UOR), the Ni₂P–Co₂P/C heterostructures exhibit superior activity and stability, attributed to the optimized geometric and electronic structures of the catalytic sites. Specifically, it takes an ultralow potential of 1.27 V to reach a current density of 10 mA cm⁻² with a small Tafel slope of 28.71 mV dec⁻¹. The operando analyses and calculation results reveal that cobalt incorporation can reduce the generation potential of the surface reconstructive active species and optimize the absorption/desorption energy of the intermediates. Overall, this study proposes an efficient and cost-effective UOR electrocatalyst and offers a new high-performance homologous heterostructure design for widespread application.     

碱性淀粉酶菌株的紫外线和He-Ne激光复合诱变的研究

以嗜碱芽胞杆菌(alkaliphilic bacillus)BC-A36为出发菌株,通过紫外线,N-甲基-N′-硝基-亚硝基胍(亚硝基胍NTG)和激光复合诱变处理,选育出一株高产碱性淀粉酶的突变株JG-57,在摇瓶发酵培养基上35~37℃培养45 h,测得酶活力稳定在867 u/mL左右,为出发菌株酶活力的2.1倍。该突变株产酶温度在25~43℃,最适温度37℃,产酶pH值7~12,最适pH值9。该酶较稳定的pH值适宜范围为9.5~10。传代实验证明,该突变株遗传性能稳定。说明激光辐照是碱性淀粉酶菌株有效的选育方法。该突变株产生的碱性淀粉酶可适用于淀粉的液化、洗涤及纺织工业等。