Revisiting the Limiting Factors for Overall Water‐Splitting on Organic Photocatalysts

In pursuit of inexpensive and earth abundant photocatalysts for solar hydrogen production from water, conjugated polymers have shown potential to be a viable alternative to widely used inorganic counterparts. The photocatalytic performance of polymeric photocatalysts, however, is very poor in comparison to that of inorganic photocatalysts. Most of the organic photocatalysts are active in hydrogen production only when a sacrificial electron donor (SED) is added into the solution, and their high performances often rely on presence of noble metal co‐catalyst (e.g. Pt). For pursuing a carbon neutral and cost‐effective green hydrogen production, unassisted hydrogen production solely from water is one of the critical requirements to translate a mere bench‐top research interest into the real world applications. Although this is a generic problem for both inorganic and organic types of photocatalysts, organic photocatalysts are mostly investigated in the half‐reaction, and have so far shown limited success in hydrogen production from overall water‐splitting. To make progress, this article exclusively discusses critical factors that are limiting the overall water‐splitting in organic photocatalysts. Additionally, we also have extended the discussion to issues related to stability, accurate reporting of the hydrogen production as well as challenges to be resolved to reach 10 % STH (solar‐to‐hydrogen) conversion efficiency.     

PDMS多层次蘑菇形微结构的制作

提出了一种基于光刻胶牺牲层技术的用于制作多层次SU-8模具的新方法,并进一步采用浇注成型的方法制作了聚二甲基硅氧烷(PDMS)多层次蘑菇形微结构。在多层次SU-8模具的制作过程中,使用了正性光刻胶BP212作为牺牲层,并采用超声辅助显影的方法使显影的时间大大缩短。通过对多层次SU-8模具预处理,有效减小了多层次SU-8模具与PDMS的结合力,从而提高了PDMS脱模的成功率。对制作的PDMS多层次蘑菇形微结构和PDMS单层次微柱结构进行了接触角测试。结果表明,PDMS多层次蘑菇形微结构的接触角为150.93°±1.6°,PDMS单层次微柱结构的接触角为139.19°±0.1°。由此可知PDMS多层次蘑菇形微结构具有优异的超疏水性能。     

Revisiting the Limiting Factors for Overall Water-Splitting on Organic Photocatalysts

In pursuit of inexpensive and earth abundant photocatalysts for solar hydrogen production from water, conjugated polymers have shown potential to be a viable alternative to widely used inorganic counterparts. The photocatalytic performance of polymeric photocatalysts, however, is very poor in comparison to that of inorganic photocatalysts. Most of the organic photocatalysts are active in hydrogen production only when a sacrificial electron donor (SED) is added into the solution, and their high performances often rely on presence of noble metal co-catalyst (e.g. Pt). For pursuing a carbon neutral and cost-effective green hydrogen production, unassisted hydrogen production solely from water is one of the critical requirements to translate a mere bench-top research interest into the real world applications. Although this is a generic problem for both inorganic and organic types of photocatalysts, organic photocatalysts are mostly investigated in the half-reaction, and have so far shown limited success in hydrogen production from overall water-splitting. To make progress, this article exclusively discusses critical factors that are limiting the overall water-splitting in organic photocatalysts. Additionally, we also have extended the discussion to issues related to stability, accurate reporting of the hydrogen production as well as challenges to be resolved to reach 10 % STH (solar-to-hydrogen) conversion efficiency.     

X-ray photoelectron spectroscopy for surface film analysis in corrosion research

Surface films on metals and alloys often protect them from reaction with the environment, and hence a knowledge of their protective properties and composition could be invaluable for predicting their corrosion behaviour. XPS (x-ray photoelectron spectroscopy) could provide a quantitative analysis of the chemical composition, the nature of valence states and elemental distribution within the surface films. The present paper reviews the potential of this technique in corrosion studies. A brief review of the work done on the passivation of iron and iron-chromium alloys and on the inhibition studies on copper base alloys has been given. A few examples of investigations carried out at authors’ laboratory are also included. An attempt has been made to establish a correlation between the compositions of the films formed and corrosion behaviour of carbon steel in 10.5 pH lithium hydroxide solution and of Cu-Ni alloys and sacrificial Al-Zn-Sn alloys in synthetic sea-water.     

Synthesis of 1,3-Diketones by Reaction of α-Haloketones with Acyl Cyanides Promoted by Samarium Diiodide

α-Haloketones reacted with acyl cyanides to form 1,3-diketones in the presence of samarium diiodide. The reaction was assumed to proceed via a mechanism involving samarium enolates formed in situ from α-haloketones.     

Sustainable Electrochemically‐Mediated Atom Transfer Radical Polymerization with Inexpensive Non‐Platinum Electrodes

Electrochemically‐mediated atom transfer radical polymerization (eATRP) of oligo(ethylene oxide) methyl ether methacrylate in water is investigated on glassy carbon, Au, Ti, Ni, NiCr and SS304. eATRPs are performed both in divided and undivided electrochemical cells operating under either potentiostatic or galvanostatic mode. The reaction is fast, reaching high conversions in ≈4 h, and yields polymers with dispersity <1.2 and molecular weights close to the theoretical values. Most importantly, eATRP in a highly simplified setup (undivided cell under galvanostatic mode) with inexpensive nonnoble metals, such as NiCr and SS304, as cathode is well‐controlled. Additionally, these electrodes neither release harmful ions in solution nor react directly with the C X chain end and can be reused several times. It is demonstrated that Pt can be replaced with cheaper, and more readily available materials without negatively affecting eATRP performance.

     

SiC MESFET工艺技术研究与器件研制

针对SiC衬底缺陷密度相对较高的问题,研究了消除或减弱其影响的工艺技术并进行了器件研制.通过优化刻蚀条件获得了粗糙度为2.07 nm的刻蚀表面;牺牲氧化技术去除刻蚀带来的表面损伤层,湿氧加干氧的氧化方式生长的SiO2钝化膜既有足够的厚度又保证了致密性良好的界面,减小了表面态对栅特性和沟道区的影响,获得了理想因子为1.17,势垒高度为0.72 eV的良好的肖特基特性;等平面工艺有效屏蔽了衬底缺陷对电极互连引线的影响,减小了反向截止漏电流,使器件在1 mA下击穿电压达到了65 V,40 V下反向漏电流为20μA.为了提高器件成品率,避免或减小衬底缺陷深能级对沟道电流的影响,使用该工艺制备的小栅宽SiCMESFET具有195 mA/mm的饱和电流密度,-15 V的夹断电压.初步测试该器件有一定的微波特性,2 GHz下测试其最大输出功率为30 dBm,增益大于5 dB.     

Photo-Curing 3D Printing of Thermosetting Sacrificial Tooling for Fabricating Fiber-Reinforced Hollow Composites

Carbon fiber-reinforced hollow composites play a vital role in lightweighting modern cars and aircrafts. Fabrication of such hollow composites with seamless internal finish requires sacrificial tooling that can be used under pressure and high temperature. For the very first time, high performance sacrificial tooling that can be used to fabricate fiber-reinforced hollow composites is produced using photocuring 3D printing technology. This is achieved by developing UV-curable resins containing highly soluble yet hydrolysable acetal acrylate cross-linker and hydrophilic 4-acryloylmorpholine monomer. It is found that the cross-linker content greatly affects the printing speed. Further, the widely adopted UV post-curing method is found to have negligible impact on improving the thermal-mechanical properties of printed structures. After thermal post-treatment, printed sacrificial tooling exhibits a heat deflection temperature of 112 °C at 0.455 MPa and an average coefficient of linear thermal expansion of 59 ppm °C⁻¹ between 30 and 100 °C. As a result, printed tooling enables fabrication of carbon fiber-reinforced hollow composites with complex geometry, which shows a tensile strength of 802 MPa and an elastic modulus of 50.2 GPa.     

On the Role of the Sr3−xCaxAl2O6 Sacrificial Layer Composition in Epitaxial La0.7Sr0.3MnO3 Membranes

The possibility to fabricate freestanding single crystal complex oxide films has raised enormous interest to be integrated in next-generation electronic devices envisaging distinct and novel properties that can deliver unprecedented performance improvement compared to traditional semiconductors. The use of the water-soluble Sr₃Al₂O₆ (SAO) sacrificial layer to detach the complex oxide film from the growth substrate has significantly expanded the complex oxide perovskite membranes library. Nonetheless, the extreme water sensitivity of SAO hinders its manipulation in ambient conditions and restricts the deposition approaches to those using high vacuum. This study presents a pioneering study on the role of Ca-substitution in solution processed SAO (Sr_3−xCa_xAl₂O₆ with x ⩽ 3) identifying a noticeable improvement on surface film crystallinity preserving a smooth surface morphology while favoring the manipulation in a less-restricted ambient conditions. Then, the study focuses on the effect of the sacrificial composition on the subsequent ex situ deposition of La_0.7Sr_0.3MnO₃ (LSMO) by pulsed laser deposition, to obtain epitaxial films with a variable degree of strain. Finally, epitaxial and strain-free LSMO membranes with metal-insulator transition at 290 K are delivered. This study offers a hybrid and versatile approach to prepare and easily manipulate crystalline perovskite oxide membranes by facilitating ex situ growth on SAO-based sacrificial layer.     

高活化铝合金牺牲阳极材料的研制

通过添加锌、铟、锡、镓等合金元素和适当的冶炼工艺，研制成功了工作电位负于－１．４０Ｖ（ＳＣＥ）、实际电容量≥２１７５Ａ．ｈ／ｋｇ、表面活性高、溶解非常均匀的铝合金牺牲阳极、该铝合金牺牲阳极在海水、淡海水介质中具有优异的电化学性能，可全面替代镁合金牺牲阳极、具有较高的技术经济优势。