Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) utilization.Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry.However,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed.Here,a hierarchical full-spectrum solar light utilization strategy is proposed.Based on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial photosynthesis.The space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics.This work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

Artificial photosynthesis for high-value-added chemicals:Old material,new opportunity

Solar energy utilization has drawn attention due to ever-increasing environmental and energy issues.Photoelectrochemical(PEC)and photocatalytic(PC)water splitting for hydrogen production,which is the most popular and well-established solar-to-chemical conversion process,has been studied thoroughly to date but is now facing limitations related to low conversion efficiency.To resolve this issue,research in PEC cells or photocatalysts has recently aimed to produce alternative value-added chemicals by modifying their redox reactions,which potentially enables high economic reward to compensate for the low efficiency.Here,various kinds of redox reactions that decouple classic water splitting reactions to produce value-added chemicals via PEC and PC processes are introduced.Successful coupling of CO_(2) reduction,O_(2) reduction and organic synthesis with either water oxidation or water reduction is comprehensively discussed from the perspective of basic fundamental and product selectivity in terms of the band structure of materials,cocatalyst design,and thermodynamics and kinetics of the reactions.Throughout the review,future challenges and opportunities are suggested with respect to the redesigned artificial synthesis,which might be an alternative development for the commercialization of PEC or PC value-added chemical production technologies in the near future.

Ligand-free CsPbBr_(3) with calliandra-like nanostructure for efficient artificial photosynthesis

The low-efficiency CO_(2) uptake capacity and insufficient photogenerated exciton dissociation of current metal halide perovskite(MHP)nanocrystals with end-capping ligands extremely restrict their application in the field of artificial photosynthesis.Herein,we demonstrate that ligand-free CsPbBr_(3) with calliandralike nanostructure(LF-CPB CL)can be synthesized easily through a ligand-free seed-assisted dissolutionrecrystallization growth process,exhibiting significantly enhanced CO_(2) uptake capacity.More specifically,the abundant surface bromine(Br)vacancies in ligand-free MHP materials are demonstrated to be beneficial to photogenerated carrier separation.The electron consumption rate of LF-CPB CL for photocatalytic CO_(2) reduction increases 7 and 20 times over those of traditional ligand-capping CsPbBr_(3)nanocrystal(L-CPB NC)and bulk CsPbBr_(3),respectively.Moreover,the absence of ligand hindrance can facilitate the interfacial electronic coupling between LF-CPB CL and tetra(4-carboxyphenyl)porphyrin iron(Ⅲ)chloride(Fe-TCPP)cocatalyst,bringing forth significantly accelerated interfacial charge separation.The LF-CPB CL/Fe-TCPP exhibits a total electron consumption rate of 145.6μmol g^(-1) h^(-1) for CO_(2)photoreduction coupled with water oxidation which is over 14 times higher than that of L-CPB NC/FeTCPP.

A NEW ARTIFICIAL PHOTOSYNTHESIS COMPOUND FOR PHOTOELECTRIC CONVERSION

A new triad model compound porphyrin-viologen-carbazole was synthesized to mimic photosynthesis.A mechanism including photoinduced electron transfer and two-step charge separation was suggested.This triad compound was easy to form LB film and rather high photodriven voltage and current were obtained with only one layer of LB film On the surface of SnO_2 conductive glass.

Design and Fabrication of Chitosan for Application of Artificial Photosynthesis

Artificial photosynthesis is a new approach to generate sustainable energy. In order to constrain reaction solution in a solid state structure and increase the reaction efficiency in artificial photosynthesis reactions, we presented two methods to fabricate the chitosan scaffold with interconnected micro channels as construction structure of a novel artificial photosynthesis device. We built 3D chitosan structure with a home-made heterogeneous 3D rapid prototyping machine, and we used lyophilization method to generate the micron-scale pores inside the chitosan scaffold. Chitosan in acetic acid could achieve different viscosities. We found a proper chitosan recipe to construct 3D scaffold by our own rapid prototyping machine. Optional support material sodium bicarbonate was used in printing 3D scaffold for holding the printed structures, and the results images indicate that this method can make the scaffold stronger and more stable.

Plasmonic semiconductors for advanced artificial photosynthesis

Plasmonic semiconductors with high free carrier concentration is a class of attractive materials that exhibit metal-like localized surface plasmon resonance(LSPR)for light extinction with tunable features.Their applications in artificial photosynthesis have witnessed considerable advances in terms of the determinants for solar-to-chemical energy conversion efficiency improvement,including light harvesting,charge dynamics as well as surface photochemistry.In this review,we begin with the fundamental introduction to physical principles and unique characters of LSPR excitation in plasmonic semiconductors.The doping strategies for activating LSPR response and the intrinsic merits in artificial photosynthesis are subsequently summarized in detail.In addition,the remaining challenging and future perspectives are briefly outlooked.We anticipate that this review can provide a tutorial guideline to broaden the horizons for plasmonic semiconductors in the exploration of sustainable plasmon-assisted photochemistry application.

Integration of metal-organic layers with quantum dots for artificial photosynthesis

Metal-organic layers(MOLs), a type of new-emerging two-dimensional ultrathin metal-organic framework materials with large surface areas and highly exposed active sites, have shown promising applications in photocatalytic CO_(2) reduction. However, due to a lack of photosensitivity and photooxidation capability, photosensitizers and sacrificial reductants are usually necessary for MOLs-based photocatalytic CO_(2) reduction systems. In this article, by integration of MOLs and quantum dots(QDs), we constructed MOLs-based catalysts with multi-functions of photosensitivity, photoreduction and photooxidation, which thus can serve as photocatalysts for CO_(2) reduction with H_(2)O as an electron donor. Specifically, by an electrostatic self-assembly approach,nickel(Ⅱ)-based MOLs(Ni-MOLs) and CsPbBr_(3)QDs have been assembled, constructing valid Ⅱ-Scheme Ni-MOLs/CsPbBr_(3) heterojunctions with close Ni-MOLs/CsPbBr_(3)heterointerface. Such a close heterointerface shortens the charge transfer distance,thus effectively boosting the charge separation and transfer. As a result, upon illumination by visible light(λ ≥ 400 nm,100 m W cm^(-2)), the optimized photocatalyst shows high efficiency and stability in photochemical CO_(2) reduction in the absence of any photosensitizers and sacrificial reductants. The CO yield reaches as high as 124 μmol g^(-1)in 4 h, over 6 times higher than that achieved by CsPbBr_(3). Additionally, the selectivity reaches 100%. This work provides a new way to construct MOL-based catalysts for artificial photosynthesis.

Artificial and Semi-artificial Photosynthesis(AP and SAP)Systems Based on Metal-Organic Frameworks

Recently,artificial and semi-artificial photosynthesis have attracted extensive attentions in addressing the crisis of energy from fossil fuels and reducing excessive CO_(2) emission.Metal-organic frameworks(MOFs)have been considered as ideal platforms for constructing artificial photosynthesis systems due to their unique properties like large specific surface area,high porosity and diverse framework topology,and tunable functionalities.This review discussed the characteristics,superiorities and challenges of MOF-based photocatalysts,and detailed summarization of several common design strategies for MOF-based artificial systems,including i)enhancement of light absorption,ii)acceleration of the charge separation and transfer,and iii)introduction of additional active units.Particularly,we give examples showing the applications of MOF-based photocatalysts,where the mechanisms of superior photocatalytic activity and selectivity are also analyzed,thereby providing theoretical guidance for rational design of MOF-based photocatalysts.Finally,the challenges and future research directions of MOF-based photocatalysts are prospected.

Visible light responsive photocatalysts developed by substitution with metal cations aiming at artificial photosynthesis

To solve resource,energy,and environmental issues,development of sustainable clean energy system is strongly required.In recent years,hydrogen has been paid much attention to as a clean energy.Solar hydrogen production by water splitting using a photocatalyst as artificial photosynthesis is a promising method to solve these issues.Efficient utilization of visible light comprised of solar light is essential for practical use.Three strategies,i.e.,doping,control of valence band,and formation of solid solution are often utilized as the useful methods to develop visible light responsive photocatalysts.This minireview introduces the recent work on visible-light-driven photocatalysts developed by substitution with metal cations of those strategies.

Wastewater treatment meets artificial photosynthesis:Solar to green fuel production,water remediation and carbon emission reduction

Current wastewater treatment(WWT)is energy-intensive and leads to vast CO_(2) emissions.Chinese pledge of“double carbon”target encourages a paradigm shift from fossil fiiels use to renewable energy harvesting during WWT.In this context,hybrid microbial photoelectrochemical(MPEC)system integrating microbial electrochemical WWT with artificial photosynthesis(APS)emerges as a promising approach to tackle water-energy-carbon challenges simultaneously.Herein,we emphasized the significance to implement energy recovery during WWT for achieving the carbon neutrality goal.Then,we elucidated the working principle of MPEC and its advantages compared with conventional APS,and discussed its potential in fulfilling energy self-sustaining WWT,carbon capture and solar fuel production.Finally,we provided a strategy to judge the carbon profit by analysis of energy and carbon fluxes in a MPEC using several common organics in wastewater.Overall,MPEC provides an alternative of WWT approach to assist carbon-neutral goal,and simultaneously achieves solar harvesting,conversion and storage.

Photosensitizing metal-organic layers for photocatalysis,artificial photosynthesis and fluorescence imaging

In recent years,metal-organic layers(MOLs)with high-density and accessible open sites have emerged as a two-dimensional version of metal-organic frameworks(MOFs)with various potential applications.Particularly,MOLs represent a promising platform for photocatalysis,artificial photosynthesis,and fluorescence imaging through the hierarchical assembly of photosensitizers and catalysts or other functional groups into MOLs.This review provides an overview of the structural design and synthesis strategies of MOLs with a particular emphasis on the applications of photosensitizing MOLs,illustrating the advantages of the MOLs-based material.The final part discusses perspectives on the challenges encountered in this field and the emerging developments that can be expected.

Artificial Photosynthesis(AP):From Molecular Catalysts to Heterogeneous Materials

The development of green and renewable energy sources is in high demand due to energy shortage and productivity development.Artificial photosynthesis(AP)is one of the most effective ways to address the energy shortage and the greenhouse effect by converting solar energy into hydrogen and other carbon-based high value-added products through the understanding of the mechanism,structural analysis,and functional simulation of natural photosynthesis.In this review,the development of AP from natural catalysts to artificial catalysts is described,and the processes of oxygen production,hydrogen production,and carbon fixation are sorted out to understand the properties and correlations of the core functional components in natural photosynthesis,to provide a better rational design and optimization for further development of advanced heterogeneous materials.

A hybrid artificial photosynthesis system with molecular catalysts covalently linked onto TiO2 as electron relay for efficient photocatalytic hydrogen evolution

Efficient charge carrier transfer from light harvesters to catalysts greatly determines the photocatalytic activity in an artificial photosynthesis(AP) system for solar hydrogen evolution.In this study,an AP system composed of xanthene dye as light harvester and cobaloxime molecular complex as catalyst,with TiO2 as electron relay,was designed for photocatalytic hydrogen evolution under visible light(λ>420 nm).It was demonstrated that with cobaloxime molecule covalently linked onto the TiO2 electron relay,the resulting hybrid AP system exhibited much increased photocatalytic activity as compared to that without TiO2.The greatly increased photocatalytic activity should be due to the efficient electron transfer from xanthene dye as light harvester and cobaloxime molecular complex as catalyst,shuttled by the TiO2 electron relay,for the following water reduction reaction.The present study demonstrates a facile and feasible strategy to guide the design of high performance AP systems through the electron relay shuttled and promoted cha rge transfer process.

Photocatalytic nitrogen fixation: An attractive approach for artificial photocatalysis

Ammonia synthesis via the Haber-Bosch process, which has been heralded as the most important invention of the 20 th century, consumes massive amounts of energy, around 1%–2% of the world’s annual energy consumption. Developing green and sustainable strategies for NH3 synthesis under ambient conditions, using renewable energy, is strongly desired, by both industrial and sci-entific researchers. Artificial photosynthesis for ammonia synthesis, which has recently attracted significant attention, directly produces NH3 from sunlight, and N2 and H2O via photocatalysis. This has been regarded as an ideal, energy-saving and environmentally-benign process for NH3 produc-tion because it can be performed under normal temperature and atmospheric pressure using re-newable solar energy. Although sustainable developments have been achieved since the pioneering work in 1977, many challenging issues（e.g., adsorption and activation of nitrogen molecules on the surface of photocatalysts under mild conditions） have still not been well solved and the photocata-lytic activities are generally low. In this miniature review, I summarize the most recent progress of photocatalytic N2 fixation for ammonia synthesis, focusing specifically on two attractive aspects for adsorption and activation of nitrogen molecules： one is engineering of oxygen vacancies, and the other is mimicking natural nitrogenase for constructing artificial systems for N2 fixation. Several representative works focusing on these aspects in artificial systems have been reported recently, and it has been demonstrated that both factors play more significant roles in photocatalytic N2 re-duction and fixation under ambient conditions. At the end of the review, I also give some remarks and perspective on the existing challenges and future directions in this field.

Chemico-biological conversion of carbon dioxide

The unabated carbon dioxide(CO_(2))emission into the atmosphere has exacerbated global climate change,resulting in extreme weather events,biodiversity loss,and an intensified greenhouse effect.To address these challenges and work toward carbon(C)neutrality and reduced CO_(2)emissions,the capture and utilization of CO_(2)have become imperative in both scientific research and industry.One cutting-edge approach to achieving efficient catalytic performance involves integrating green bioconversion and chemical conversion.This innovative strategy offers several advantages,including environmental friendliness,high efficiency,and multi-selectivity.This study provides a comprehensive review of existing technical routes for carbon sequestration(CS)and introduces two novel CS pathways:the electrochemicalbiological hybrid and artificial photosynthesis systems.It also thoroughly examines the synthesis of valuable Cnproducts from the two CS systems employing different catalysts and biocatalysts.As both systems heavily rely on electron transfer,direct and mediated electron transfer has been discussed and summarized in detail.Additionally,this study explores the conditions suitable for different catalysts and assesses the strengths and weaknesses of biocatalysts.We also explored the biocompatibility of the electrode materials and developed novel materials.These materials were specifically engineered to combine with enzymes or microbial cells to solve the biocompatibility problem,while improving the electron transfer efficiency of both.Furthermore,this review summarizes the relevant systems developed in recent years for manufacturing different products,along with their respective production efficiencies,providing a solid database for development in this direction.The novel chemical-biological combination proposed herein holds great promise for the future conversion of CO_(2)into advanced organic compounds.Additionally,it offers exciting prospects for utilizing CO_(2)in synthesizing a wide range of industrial products.Ultimately,the present study provides a unique perspective for achieving the vital goals of“peak shaving”and C-neutrality,contributing significantly to our collective efforts to combat climate change and its associated challenges.

Influence of O-O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation

Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipathic Ru(bda)-based catalysts(bda=2,2'-bipyrdine-6,6'-dicarbonoxyl acid)and aliphatic chain decorated electrode surfaces,forming lipid bilayer membrane(LBM)-like structures.The Ru(bda)catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O-O formation mechanisms.However,compared to the slow charge transfer process,the O-O formation pathways did not determine the PEC water oxidation efficiency of the dyesensitized photoanodes,and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs.Instead,charge transfer plays a decisive role in the PEC water oxidation rate.When an indolo[3,2-b]carbazole derivative was introduced between the Ru(bda)catalysts and aliphatic chain-modified photosensitizer in LBM films,serving as a charge transfer mediator for the tyrosine-histidine pair in PSⅡ,the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced.

Is platinum-loaded titania the best material for dye-sensitized hydrogen evolution under visible light?

A dye-sensitized photocatalyst combining Pt-loaded TiO_(2) and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)Nb_(3)O_(10) nanosheets.When the sacrificial donor ethylenediaminetetraacetic acid(EDTA)disodium salt dihydrate was used,RuP/Pt/TiO_(2) showed higher activity than RuP/Pt/HCa_(2)Nb_(3)O_(10).In contrast,when NaI(a reversible electron donor)was used,RuP/Pt/TiO_(2) showed little activity due to back electron transfer to the electron acceptor(I_(3)-),which was gener-ated as the oxidation product of I-.By modification with anionic polymers(sodium poly(styrenesulfonate)or sodium polymethacrylate)that could inhibit the scavenging of conduction band electrons by I_(3)-,the H_(2) production activity from aqueous NaI was improved,but it did not exceed that of RuP/Pt/HCa_(2)Nb_(3)O_(10).Transient absorption measurements showed that the rate of semiconductor-to-dye back electron transfer was slower in the case of TiO_(2) than HCa_(2)Nb_(3)O_(10),but the electron transfer reaction to I3-was much faster.These results indicate that Pt/TiO_(2) is useful for reactions with sacrificial reductants(e.g.,EDTA),where the back electron transfer reaction to the more reducible product can be neglected.However,more careful design of the catalyst will be nec-essary when a reversible electron donor is employed.

Role of transition-metal electrocatalysts for oxygen evolution with Si-based photoanodes

A comprehensive understanding of the role of the electrocatalyst in photoelectrochemical(PEC)water splitting is central to improving its performance.Herein,taking the Si-based photoanodes(n^(+)p-Si/SiO_(x)/Fe/FeOx/MOOH,M=Fe,Co,Ni)as a model system,we investigate the effect of the transition-metal electrocatalysts on the oxygen evolution reaction(OER).Among the photoanodes with the three different electrocatalysts,the best OER activity,with a low-onset potential of∼1.01 VRHE,a high photocurrent density of 24.10 mA cm^(-2)at 1.23 VRHE,and a remarkable saturation photocurrent density of 38.82 mA cm^(-2),was obtained with the NiOOH overlayer under AM 1.5G simulated sunlight(100 mW cm^(-2))in 1 M KOH electrolyte.The optimal interfacial engineering for electrocatalysts plays a key role for achieving high performance because it promotes interfacial charge transport,provides a larger number of surface active sites,and results in higher OER activity,compared to other electrocatalysts.This study provides insights into how electrocatalysts function in water-splitting devices to guide future studies of solar energy conversion.

Photoelectrocatalytic CO2 reduction based on metalloporphyrin-modified TiO2 photocathode

The conversion of CO2 and water to value-added chemicals under sunlight irradiation, especially by photoelectrocatalytic reduction process, is always a dream for human beings. A new artificial photosynthesis system composed of a metalloporphyrin-functionalized TiO2 photocathode and BiVO4 photoanode can efficiently transform CO2 and water to methanol, which is accompanied by oxygen release. This photoelectrocatalytic system smoothly produces methanol at a rate of 55.5 μM h^–1 cm^– 2, with 0.6 V being the membrane voltage in plants. The production of hydrogen can also be observed when the voltage is more than 0.75 V, due to photocatalysis. Our results evidently indicate that the molecules of metalloporphyrin attached onto the surface of anatase (TiO2) behave as chlorophyll, NADP, and Calvin cycle in plant cells.

Artificial Mn4-oxido complexes mimic the oxygen-evolving center in photosynthesis

The understanding of the structure-function relationship of the oxygen-evolving center(OEC), a Mn_4 Cacluster, in photosystem II is impeded mainly due to the complexity of the protein environment and lack of rational chemical models as a reference. In this study, two novel Mn_4-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [Mn_4~Ⅲ] core are provided by eight μ_2-carboxylate groups and two neutral terminal ligands(pyridine or isoquinoline). This type of peripheral ligation is very similar to the Mn_4Ca-oxide model complexes recently reported to mimic the OEC. The new Mn_4-oxide complex can catalyze the oxygen-evolving reaction in the presence of Bu^tOOH as an oxidant. The structure and redox properties comparison of the Mn_4-oxido and Mn_4Ca-oxido complexes provide important clues to understanding the functional role of Ca in the OEC in natural photosynthesis, and develop more efficient artificial catalysts for the water-splitting reaction in the future.