Research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts

With the increasing concerns to energy shortage and environmental problems in modern society,the development of cheap,clean,and sustainable energy alternatives has been attracting tremendous attention globally.Among various strategies of renewable energy exploration,solar-driven water splitting into its compositional elements H2 and O2 is an ideal approach to convert and store renewable solar energy into chemical bonds.In recent few decades,as an emerging new type of catalysts,polyoxometalates(POMs)have been widely utilized for water splitting due to their versatile synthetic methodology and highly tunable physicochemical and photochemical properties.This critical review addresses the research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts,including plenary POMs,transition-metal-substituted POMs,POM@MOF composites,and POM-semiconductor hybrids,under UV,near UV and visible light irradiation.In addition,the catalytic mechanism for each reaction system has been thoroughly discussed and summarized.Finally,a comprehensive outlook of this research area is also prospected.

Dye-Enhanced Self-Electrophoretic Propulsion of Light-Driven TiO_2–Au Janus Micromotors

Light-driven synthetic micro-/nanomotors have attracted considerable attention in recent years due to their unique performances and potential applications. We herein demonstrate the dye-enhanced self-electrophoretic propulsion of light-driven Ti O_2–Au Janus micromotors in aqueous dye solutions. Compared to the velocities of these micromotors in pure water, 1.7, 1.5, and 1.4 times accelerated motions were observed for them in aqueous solutions of methyl blue(10-5g L^(-1)), cresol red(10^(-4)g L^(-1)),and methyl orange(10^(-4)g L^(-1)), respectively. We determined that the micromotor speed changes depending on thetype of dyes, due to variations in their photodegradation rates. In addition, following the deposition of a paramagnetic Ni layer between the Au and Ti O_2 layers, the micromotor can be precisely navigated under an external magnetic field. Such magnetic micromotors not only facilitate the recycling of micromotors, but also allow reusability in the context of dye detection and degradation.In general, such photocatalytic micro-/nanomotors provide considerable potential for the rapid detection and ‘‘on-thefly'' degradation of dye pollutants in aqueous environments.

Wheel-shaped icosanuclear Cu-containing polyoxometalate catalyst: Mechanistic and stability studies on light-driven hydrogen generation

In this paper,we report the synthesis and characterization of a wheel-shaped icosanuclear Cu-containing polyoxometalate(POM),K_(12)Li_(13)[Cu_(2)0Cl(OH)_(24)(H_(2)O)_(12)(P_(8)W_(48)O_(184))]·22H_(2)O(K_(12)Li_(13)-Cu_(2)0P_(8)W_(48)).The resulting cation-exchanged tetrabutylammonium salt of the polyoxoanion Cu_(2)0P_(8)W_(48)(TBA-Cu_(2)0P_(8)W_(48))exhibits high efficiency for visible-light-driven H_(2) production in the presence of an[Ir(ppy)2(dtbbpy)][PF_(6)]photosensitizer and a triethanolamine electron donor.Under optimal conditions,the turnover number for H_(2) production reaches~2892 after 5 h of photocatalysis and thereafter continuously increases to~13400 in a long-term 120 h reaction,representing the best performance among all reported transition-metal-substituted POM catalysts.Mechanistic studies confirm the existence of reductive and oxidative quenching processes,of which the reductive quenching pathway is dominant.Various stability tests demonstrate that the TBA-Cu_(2)0P_(8)W_(48) catalyst slowly dissociates Cu ions under turnover conditions;however,both the starting TBA-Cu_(2)0P_(8)W_(48) and its molecular decomposition products are dominant active species for efficient and long-term H_(2) production.

Current–Voltage Characteristics of the Aziridine-Based Nano-Molecular Wires: a Light-Driven Molecular Switch

Using nonequilibrium Green＇s function formalism combined first-principles density functional theory, we analyze the transport properties of a 4,4-dimethyl-6-（4-nitrophenyl）-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene molecular optical switch. The title molecule can convert between closed and open forms by visible or ultraviolet irradiation. The I-V characteristics, differential conductance, on-off ratio, electronic transmission coefficients, spatial distribution of molecular projected self-consistent Hamiltonian orbitals, HOMO-LUMO gaps, effect of electrode materials Y（111）（Y =Au, Ag and Pt） on electronic transport and different molecular geometries corresponding to the closed and open forms through the molecular device are discussed in detail. Based on the results, as soon as possible the open form translates to the closed form, and there is a switch from the ON state to the OFF state（low resistance switches to high resistance）. Theoretical results show that the donor/acceptor substituent plays an important role in the electronic transport of molecular devices. The switching performance can be improved to some extent through suitable donor and acceptor substituents.

A Micro-Sized Light-Driven Pico-Second Oscillator

Light carries linear momentum and can therefore exert a radiation force on the objects that it encounters. This established fact enabled optical manipulation of micro/nano-sized objects, as well as macroscopic objects such as solar sails, among many other important applications. While these efforts benefit from the average value of light’s linear momentum, in this article, we propose exploiting the temporal variation of light’s linear momentum to achieve an oscillatory force of microNewton amplitude and picosecond period. We validate our proposal by analytical calculations and time domain simulations of Maxwell’s equations in the case of a high-index quarter-wave slab irradiated by a terahertz plane electromagnetic wave. In particular, we show that for plane wave terahertz light of electric field amplitude 5000 V/m and frequency 4.8 THz, an oscillatory radiation pressure of amplitude 1.8 × 10-4 N/m2 and 0.1 ps period can be achieved.

Visible light-driven oxidation of non-native substrate by laccase attached on Ru-based metal-organic frameworks

Light-induced electron transfer can broaden the substrate range of metalloenzyme.However,the efficiency of photo-enzyme coupling is limited by the poor combination of photosensitizer or photocatalyst with enzyme.Herein,we prepared the nano-photocatalyst MIL-125-NH_(2)@Ru(bpy)by in site embedding ruthenium pyridine-diimine complex[Ru(bpy)_(3)^(2+)into metal organic frameworks MIL-125-NH_(2)and associated it with multicopper oxidase(MCO)laccase.Compared to[Ru(bpy)_(3)]^(2+),the coupling efficiency of MIL-125-NH_(2)@Ru(bpy)_(3)for enzymatic oxygen reduction increased by 35.7%.A series of characterizations confirmed that the amino group of laccase formed chemical bonds with the surface defects or hydrophobic groups of MIL-125-NH_(2)@Ru(bpy)_(3).Consequently,the tight binding accelerated the quenching process and electron transfer between laccase and the immobilized ruthenium pyridine-diimine complex.This work would open an avenue for the synthesis of MOFs photocatalyst towards photo-enzyme coupling.

Light-driven soft actuator based on graphene and WSe2 nanosheets composite for multimodal motion and remote manipulation

Remote controlled soft actuators have attracted ever-increasing interest in industrial,medical,robotics,and engineering fields.Soft actuators are charming than normal tools in executing dedicate tasks due to small volume and flexible body they have.However,it remains a challenge to design soft actuator that can adapt to multi-environments under remote stimuli with promising nano materials.Herein,we have developed a kind of near-infrared laser driven soft actuators with multi locomotive modes based on WSe2 and graphene nanosheets heterojunction.Different locomotion modes are driven by photothermal effect induced deformation to adapt to different working conditions.Moreover,the specially designed gripper driven by pulsed laser can lift a heavy load which is four times of its weight.This work broadens the choice of advanced nanomaterials for photothermal conversion of soft actuators.It is promising to realize applications including photothermal therapy and complex environment detection through the combination of the intelligent robot design and optical fiber system.

Near-infrared light-driven Janus capsule motors： Fabrication, propulsion, and simulation

We report a fuel-free, near-infrared （NIR）-driven Janus microcapsule motor. The Janus microcapsule motors were fabricated by template-assisted polyelectrolyte layer-by-layer assembly, followed by spraying of a gold layer on one side. The NIR-powered Janus motors achieved high propulsion with a maximum speed of 42μm.s-1 in water. The propulsion mechanism of the Janus motor was attributed to the self-thermophoresis effect： The asymmetric distribution of the gold layer generated a local thermal gradient, which in turn generated thermophoretic force to propel the Janus motor. Such NIR-propelled Janus capsule motors can move efficiently in cell culture medium and have no obvious effects on the cell at the power of the NIR laser, indicating considerable promise for future biomedical applications.

光控仿生液晶弹性体软执行器

随着自然界的不断进化,许多生物都表现出了适应环境的独特行为,为研究人员开发适应环境的智能材料和仿生软执行器提供了灵感。液晶弹性体(Liquid Crystal Elastomers,LCEs)软执行器作为智能软机器人的代表性执行元件,具有液晶各向异性和橡胶软弹性,在外部环境刺激下能够实现可逆、复杂的形状变化和运动能力。基于光驱动的LCEs执行器具备多种优势,包括强大的远程控制能力、迅速的响应时间以及高效的能量积累和释放机制。本文介绍了光控仿生LCEs软执行器中的LCEs形状变化响应机制及其性能,并展望了基于仿生设计的光控LCEs软执行器在智能机器人领域的应用前景。

光驱动下的低碳化技术应用——以雄安站为例

建筑碳排放是我国实现碳达峰、碳中和目标的重要方向。可分为建材生产及运输阶段碳排放、建筑建造阶段碳排放、建筑运营及维护阶段碳排放、建筑拆除阶段碳排放。其中建筑运营阶段碳排放量占到建筑全生命周期中碳排放量的50%以上,因此狠抓运营阶段碳排放是实现建筑领域“双碳”目标的关键。高铁站房作为大型交通建筑,因其客流量大、运营周期长、系统复杂、设备众多等原因,在其运营期间不仅能耗高而且碳排放量巨大,对城市环境造成了极大的负面效应,因此对铁路站房的减碳研究尤为重要。以雄安站为例,定量分析“光驱动”下的站房减碳效果,进而为同类型建筑的减碳工作提供参考。

Hydrothermal fabrication and visible-light-driven photocatalytic properties of bismuth vanadate with multiple morphologies and/or porous structures for Methyl Orange degradation

Monoclinic BiVO4 with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniques. The photocatalytic activities of the BiVO4 materials were evaluated for the degradation of Methyl Orange under visible-light irradiation. It is observed that pH value and surfactant exerted a great effect on the morphology and pore structure of the BiVO4 product. Spherical BiVO4 with porous structures, flower-cluster-like BiVO4, and flower-bundle-like BiVO4 were generated hydrothermally at 100°C with poly（vinyl pyrrolidone） （PVP） and urea （pH = 2） and at 160°C with NaHCO3 （pH = 7 and 8）, respectively. The PVP-derived BiVO4 showed much higher surface areas （5.0-8.4 m2/g） and narrower bandgap energies （2.45-2.49 eV）. The best photocatalytic performance of the spherical BiVO4 material with a surface area of 8.4 m2/g was associated with its higher surface area, narrower bandgap energy, higher surface oxygen vacancy density, and unique porous architecture.

Light-driven crystallization of polystyrene micro-spheres

We investigate the dynamic crystallization processes of colloidal photonic crystals, which are potentially invaluable for solving a number of existing and emerging technical problems in regards to controlled fabrication of crystals, such as size normalization, stability improvement, and acceleration of synthesis. In this paper, we report systematic high-resolution optical observation of the spontaneous crystallization of monodisperse polystyrene(PS) micro-spheres in aqueous solution into close-packed arrays in a static line optical tweezers. The experiments demonstrate that the crystal structure is mainly affected by the minimum potential energy of the system; however, the crystallization dynamics could be affected by various mechanical, physical, and geometric factors. The complicated dynamic transformation process from 1D crystallization to 2D crystallization and the creation and annihilation of dislocations and defects via crystal relaxation are clearly illustrated.Two major crystal growth modes, the epitaxy growth pattern and the inserted growth pattern, have been identified to play a key role in shaping the dynamics of the 1D and 2D crystallization process. These observations offer invaluable insights for in-depth research about colloidal crystal crystallization.

宜居城市环境品质提升关键问题与研究路径

我国城市已迈入以品质提升为主的转型发展新阶段,宜居环境建设成为城市发展的新理念、新目标。本文介绍了“城市可度量、居民能感知、方法更本土、技术高融合”的城市环境品质提升策略与路线,重点阐述了“宜居城市环境品质评价和提升的本土化理论方法”“城市道路慢行系统与空间环境的适应性改造”“城市声、光、热环境品质的协同提升”与“城市宜居环境综合品质预测模型及应用”四大关键问题,以期构筑“新标尺”,支撑对城市环境品质的精确测度与科学提升。此外,本研究还就数智技术驱动下城市环境品质提升模式的创新与变革进行了探讨。

极紫外光电效应电荷驱动仿真与试验验证

惯性传感器中的检验质量是精密引力测量系统中的核心,其表面会因为宇宙高能粒子持续注入而积累电荷,在惯性传感器内部电磁场作用下产生杂散噪声,影响精密引力测量结果.根据光电效应原理,用UV LED产生极紫外光照射惯性传感器的电极与检验质量表面,并在电极间施加适当电场,就可以在不引入外力作用且无接触条件下改变检验质量的电荷量.本文基于平行板电容器的简化电极模型,对极紫外电荷驱动过程进行了理论建模仿真.在此基础上设计和构建了一套电荷驱动验证试验系统,针对光功率、偏置电压对充放电速率的影响和交流电荷驱动进行试验.试验证明电荷充放电速率与极紫外光功率成正比,其量子产率随极板间电场强度变化.最终可实现稳定控制检验质量电荷放电速率在0.31~0.76 pC⋅s^(–1),检验质量电荷充电速率在–0.05~–0.17 pC⋅s^(–1).分析提出的检验质量电荷充放电速率理论模型与地面试验结果一致,可以有力支撑电荷管理控制系统的研制.

基于MATLAB结构光投影的三维重建实验教学

在基于结构光投影的双目立体视觉三维轮廓测量综合性实践课程中引入项目驱动式教学法,以知识实践及运用为培养目标,提升学生解决实际工程问题的能力和创新能力。在课程设计上,项目具有一定难度,学生需自主搭建结构光实验台进行投影、采图及MATLAB图像处理,从而充分提升动手能力和独立思考能力。实验内容涵盖课程的核心知识点,实验过程具有挑战性。经过教学实践,获得了高质量的教学效果。

Visible-light-driven photocatalytic degradation of rhodamine B using Bi_(2)WO_(6)/GO deposited on polyethylene terephthalate fabric

The environmental repercussions of wastewater from the dye process mean that it is very important to obtain an eco-friendly photocatalyst that would degrade wastewater.Herein,bismuth tungstate/graphene oxide(Bi_(2)WO_(6)/GO)composites are fabricated through in-situ hydrothermal reaction and then the Bi_(2)WO_(6)/GO photocatalysts are deposited onto polyethylene terephthalate(PET)fabric.The obtained Bi_(2)WO_(6)/GO deposited PET fabrics are then characterized through XPS,Raman,SEM,TEM,XRD,UV-vis,BET method and photoluminescence spectroscopy(PL)to investigate their chemical and crystal structures,morphology,optical property,surface area and photochemical properties.Photocatalytic performance is studied through examining the rate of degrading rhodamine B(RhB)under visible light.Surface of PET fibers is densely covered with Bi_(2)WO_(6)/GO.Bi_(2)WO_(6)/GO deposited PET fabrics show a broad absorption band in the visible spectra.Removal rate of RhB on the Bi_(2)WO_(6)/GO deposited PET fabric is the highest with the GO content of 2 g/L(labeled as Bi_(2)WO_(6)/2 g/LGO).The result of active species experiment shows that superoxide radicals(·O_(2)^(−))plays a major role in the degradation of RhB.Moreover,Bi_(2)WO_(6)/2 g/LGO deposited PET fabric shows excellent cycle stability of photocatalytic degradation for RhB.The findings in this work can be extended to preparation other types of composite on the textile for photocatalysis,which can be applied to remove dyes in the wastewater produced by the textile or leather industry.

Cytochrome P450s in algae:Bioactive natural product biosynthesis and light-driven bioproduction

Algae are a large group of photo synthetic organisms responsible for approximately half of the earth’s total photosynthesis.In addition to their fundamental ecological roles as oxygen producers and as the food base for almost all aquatic life,algae are also a rich source of bioactive natural products,including several clinical drugs.Cytochrome P450 enzymes(P450s) are a superfamily of biocatalysts that are extensively involved in natural product biosynthesis by mediating various types of reactions.In the post-genome era,a growing number of P450 genes have been discovered from algae,indicating their important roles in algal life-cycle.However,the functional studies of algal P450s remain limited.Benefitting from the recent technical advances in algae cultivation and genetic manipulation,the researches on P450s in algal natural product biosynthesis have been approaching to a new stage.Moreover,some photoauto trophic algae have been developed into "photo-bioreactors" for heterologous P450s to produce high-value added pharmaceuticals and chemicals in a carbon-neutral or carbon-negative manner.Here,we comprehensively review these advances of P450 studies in algae from 2000 to 2021.

Bidirectional Light-Driven Ion Transport through Porphyrin Metal–Organic Framework-Based van der Waals Heterostructures via pH-Induced Band Alignment Inversion

Heterogeneous two-dimensional layered membranes reconstructed fromnatural or synthetic van derWaals materials enable novel ion transport mechanisms by coupling with the chemical and optoelectronic properties of the layered constituents.Here,we report a light-driven and pH-dependent bidirectional ion transport phenomenon through porphyrin metal–organic framework(PMOF)and transition metal dichalcogenides-based multilayer van der Waals heterostructures with sub-nanometer ionic channels.

Direct observation of the clockwise light-driven rotation of F_0F_(1-)ATP synthase complex

The purified thermophilic bacterium PS3 F1β10×His-tag is inserted into the F0F1-ATP synthases of chromatophores isolated from photosynthetic bacteria Rhodospirillum rubrum. The studies of biochemical properties of the hybrid chromatophores show that they have both protons-driving capability and photophosphorylation. The fluorescent actin filaments, as a marker of its orientation by video-microscopic experiment, are connected via Maleimido-C3-NTA to the reconstituted β10×His-tag of F0F1-ATP synthases.The clockwise rotation of FoFt-ATP synthases driven by light is observed directly when viewed from the Fo side to Ft. This system should be valuable for further studying the coupling property of F0F1-ATP synthase.

Recent advancement and future challenges of photothermal catalysis for VOCs elimination:From catalyst design to applications

Photothermal catalysis realizes the synergistic effect of solar energy and thermochemistry,which also has the potential to improve the reaction rate and optimize the selectivity.In this review,the research progress of photothermal catalytic removal of volatile organic compounds(VOCs)by nano-catalysts in recent years is systematically reviewed.First,the fundamentals of photothermal catalysis and the fabrication of catalysts are described,and the design strategy of optimizing photothermal catalysis performance is proposed.Second,the performance for VOC degradation with photothermal catalysis is evaluated and compared for the batch and continuous systems.Particularly,the catalytic mechanism of VOC oxidation is systematically introduced based on experimental and theoretical study.Finally,the future limitations and challenges have been discussed,and potential research directions and priorities are highlighted.A broad view of recent photothermal catalyst fabrication,applications,challenges,and prospects can be systemically provided by this review.