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Dinuclear metal synergistic catalysis (DMSC) has been proved an effective approach to enhance catalytic efficiency in photocatalytic CO2 reduction reaction, while it remains challenge to design dinuclear metal complexes that can show DMSC effect. The main reason is that the influence of the microenvironment around dinuclear metal centres on catalytic activity has not been well recognized and revealed. Herein, we report a dinuclear cobalt complex featuring a planar structure, which displays outstanding catalytic efficiency for photochemical CO2‐to‐CO conversion. The turnover number (TON) and turnover frequency (TOF) values reach as high as 14457 and 0.40 s−1 respectively, 8.6 times higher than those of the corresponding mononuclear cobalt complex. Control experiments and theoretical calculations revealed that the enhanced catalytic efficiency of the dinuclear cobalt complex is due to the indirect DMSC effect between two CoII ions, energetically feasible one step two‐electron transfer process by Co2I,I intermediate to afford Co2II,II(CO22−) intermediate and fast mass transfer closely related with the planar structure. [ABSTRACT FROM AUTHOR]

Hydrogen‐bonded organic frameworks (HOFs) are outstanding candidates for photocatalytic hydrogen evolution. However, most of reported HOFs suffer from poor stability and photocatalytic activity in the absence of Pt cocatalyst. Herein, a series of metal HOFs (Co2‐HOF‐X, X=COOMe, Br, tBu and OMe) have been rationally constructed based on dinuclear cobalt complexes, which exhibit exceptional stability in the presence of strong acid (12 M HCl) and strong base (5 M NaOH) for at least 10 days. More impressively, by varying the ‐X groups of the dinuclear cobalt complexes, the microenvironment of Co2‐HOF‐X can be modulated, giving rise to obviously different photocatalytic H2 production rates, following the −X group sequence of −COOMe>−Br>−tBu>−OMe. The optimized Co2‐HOF‐COOMe shows H2 generation rate up to 12.8 mmol g−1 h−1 in the absence of any additional noble‐metal photosensitizers and cocatalysts, which is superior to most reported Pt‐assisted photocatalytic systems. Experiments and theoretical calculations reveal that the −X groups grafted on Co2‐HOF‐X possess different electron‐withdrawing ability, thus regulating the electronic structures of Co catalytic centres and proton activation barrier for H2 production, and leading to the distinctly different photocatalytic activity. [ABSTRACT FROM AUTHOR]

Solar‐driven CO2 reduction and water oxidation to liquid fuels represents a promising solution to alleviate energy crisis and climate issue, but it remains a great challenge for generating CH3OH and CH3CH2OH dominated by multi‐electron transfer. Single‐cluster catalysts with super electron acceptance, accurate molecular structure, customizable electronic structure and multiple adsorption sites, have led to greater potential in catalyzing various challenging reactions. However, accurately controlling the number and arrangement of clusters on functional supports still faces great challenge. Herein, we develop a facile electrosynthesis method to uniformly disperse Wells‐Dawson‐ and Keggin‐type polyoxometalates on TiO2 nanotube arrays, resulting in a series of single‐cluster functionalized catalysts P2M18O62@TiO2 and PM12O40@TiO2 (M=Mo or W). The single polyoxometalate cluster can be distinctly identified and serves as electronic sponge to accept electrons from excited TiO2 for enhancing surface‐hole concentration and promote water oxidation. Among these samples, P2Mo18O62@TiO2‐1 exhibits the highest electron consumption rate of 1260 μmol g−1 for CO2‐to‐CH3OH conversion with H2O as the electron source, which is 11 times higher than that of isolated TiO2 nanotube arrays. This work supplied a simple synthesis method to realize the single‐dispersion of molecular cluster to enrich surface‐reaching holes on TiO2, thereby facilitating water oxidation and CO2 reduction. [ABSTRACT FROM AUTHOR]

The construction of secondary building units (SBUs) in versatile metal–organic frameworks (MOFs) represents a promising method for developing multi‐functional materials, especially for improving their sensitizing ability. Herein, we developed a dual small molecules auxiliary strategy to construct a high‐nuclear transition‐metal‐based UiO‐architecture Co16‐MOF‐BDC with visible‐light‐absorbing capacity. Remarkably, the N3− molecule in hexadecameric cobalt azide SBU offers novel modification sites to precise bonding of strong visible‐light‐absorbing chromophores via click reaction. The resulting Bodipy@Co16‐MOF‐BDC exhibits extremely high performance for oxidative coupling benzylamine (~100 % yield) via both energy and electron transfer processes, which is much superior to that of Co16‐MOF‐BDC (31.5 %) and Carboxyl @Co16‐MOF‐BDC (37.5 %). Systematic investigations reveal that the advantages of Bodipy@Co16‐MOF‐BDC in dual light‐absorbing channels, robust bonding between Bodipy/Co16 clusters and efficient electron‐hole separation can greatly boost photosynthesis. This work provides an ideal molecular platform for synergy between photosensitizing MOFs and chromophores by constructing high‐nuclear transition‐metal‐based SBUs with surface‐modifiable small molecules. [ABSTRACT FROM AUTHOR]

The development of high‐performance photocatalytic systems for CO2 reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb‐free halide perovskite Cs2AgBiBr6 nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 μmol g−1 h−1 for visible‐light‐driven CO2‐to‐CO conversion coupled with water oxidation to O2, over 8 times of the unmodified Cs2AgBiBr6 (36±8 μmol g−1 h−1), also far surpassing the documented systems (<150 μmol g−1 h−1). Besides the improved intrinsic activity, electrochemical, computational, ex‐/in situ X‐ray photoelectron and X‐ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs2AgBiBr6 can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have been widely studied in photocatalytic CO2 reduction reaction (CO2RR). However, pristine COFs usually exhibit low catalytic efficiency owing to the fast recombination of photogenerated electrons and holes. In this study, we fabricated a stable COF‐based composite (GO‐COF‐366‐Co) by covalently anchoring COF‐366‐Co on the surface of graphene oxide (GO) for the photocatalytic CO2 reduction. Interestingly, in absolute acetonitrile (CH3CN), GO‐COF‐366‐Co shows a high selectivity of 94.4 % for the photoreduction of CO2 to formate, with a formate yield of 15.8 mmol/g, which is approximately four times higher than that using the pristine COF‐366‐Co. By contrast, in CH3CN/H2O (v : v=4 : 1), the main product for the photocatalytic CO2 reduction over GO‐COF‐366‐Co is CO (96.1 %), with a CO yield as high as 52.2 mmol/g, which is also approximately four times higher than that using the pristine COF‐366‐Co. Photoelectrochemical experiments demonstrate the covalent bonding of COF‐366‐Co and GO to form the GO‐COF‐366‐Co composite facilitates charge separation and transfer significantly, thereby accounting for the enhanced catalytic activity. In addition, theoretical calculations and in situ Fourier transform infrared spectroscopy reveal H2O can stabilize the *COOH intermediate to further form a *CO intermediate via O−H(aq)⋅⋅⋅O(*COOH) hydrogen bonding, thus explaining the regulated photocatalytic performance. [ABSTRACT FROM AUTHOR]

The sensitizing ability of a catalytic system is closely related to the visible‐light absorption ability, excited‐state lifetime, redox potential, and electron‐transfer rate of photosensitizers (PSs), however it remains a great challenge to concurrently mediate these factors to boost CO2 photoreduction. Herein, a series of Ir(III)‐based PSs (Ir‐1–Ir‐6) were prepared as molecular platforms to understand the interplay of these factors and identify the primary factors for efficient CO2 photoreduction. Among them, less efficient visible‐light absorption capacity results in lower CO yields of Ir‐1, Ir‐2 or Ir‐4. Ir‐3 shows the most efficient photocatalytic activity among these mononuclear PSs due to some comprehensive parameters. Although the Kobs of Ir‐3 is ≈10 times higher than that of Ir‐5, the CO yield of Ir‐3 is slightly higher than that of Ir‐5 due to the compensation of Ir‐5's strong visible‐light‐absorbing ability. Ir‐6 exhibits excellent photocatalytic performance due to the strong visible‐light absorption ability, comparable thermodynamic driving force, and electron transfer rate among these PSs. Remarkably, the CO2 photoreduction to CO with Ir‐6 can achieve 91.5 μmol, over 54 times higher than Ir‐1, and the optimized TONC‐1 can reach up to 28160. Various photophysical properties of the PSs were concurrently adjusted by fine ligand modification to promote CO2 photoreduction. [ABSTRACT FROM AUTHOR]

Alkaline fuel cells can permit the adoption of platinum group metal‐free (PGM‐free) catalysts and cheap bipolar plates, thus further lowering the cost. With the exploration of PGM‐free hydrogen oxidation reaction (HOR) catalysts, nickel‐based compounds have been considered as the most promising HOR catalysts in alkali. Here we report an interfacial engineering through the formation of nickel‐vanadium oxide (Ni/V2O3) heterostructures to activate Ni for efficient HOR catalysis in alkali. The strong electron transfer from Ni to V2O3 could modulate the electronic structure of Ni sites. The optimal Ni/V2O3 catalyst exhibits a high intrinsic activity of 0.038 mA cm−2 and outstanding stability. Experimental and theoretical studies reveal that Ni/V2O3 interface as the active sites can enable to optimize the hydrogen and hydroxyl bindings, as well as protect metallic Ni from extensive oxidation, thus achieving the notable activity and durability. [ABSTRACT FROM AUTHOR]

We explored a co‐dissolved strategy to embed mono‐dispersed Pt center into V2O5 support via dissolving [PtV9O28]7− into [V10O28]6− aqueous solution. The uniform dispersion of [PtV9O28]7− in [V10O28]6− solution allows [PtV9O28]7− to be surrounded by [V10O28]6− clusters via a freeze‐drying process. The V centers in both [PtV9O28]7− and [V10O28]6− were converted into V2O5 via a calcination process to stabilize Pt center. These double separations can effectively prevent the Pt center agglomeration during the high‐temperature conversion process, and achieve 100 % utilization of Pt in [PtV9O28]7−. The resulting Pt‐V2O5 single‐atom‐site catalysts exhibit a CH4 yield of 247.6 μmol g−1 h−1, 25 times higher than that of Pt nanoparticle on the V2O5 support, which was accompanied by the lactic acid photooxidation to form pyruvic acid. Systematical investigations on this unambiguous structure demonstrate an important role of Pt−O atomic pair synergy for highly efficient CO2 photoreduction. [ABSTRACT FROM AUTHOR]

Dual‐atom catalysts (DACs) have emerged as efficient electrocatalysts for CO2 reduction owing to the synergistic effect between the binary metal sites. However, rationally modulating the electronic structure of DACs to optimize the catalytic performance remains a great challenge. Herein, we report the electronic structure modulation of three Ni2 DACs (namely, Ni2−N7, Ni2−N5C2 and Ni2−N3C4) by the regulation of the coordination environments around the dual‐atom Ni2 centres. As a result, Ni2−N3C4 exhibits significantly improved electrocatalytic activity for CO2 reduction, not only better than the corresponding single‐atom Ni catalyst (Ni−N2C2), but also higher than Ni2−N7 and Ni2−N5C2 DACs. Density functional theory (DFT) calculations revealed that the high electrocatalytic activity of Ni2−N3C4 for CO2 reduction could be attributed to the electronic structure modulation to the Ni centre and the resulted proper binding energies to COOH* and CO* intermediates. [ABSTRACT FROM AUTHOR]

Regulating intermediates through elaborate catalyst design to control the reaction direction is crucial for promoting the selectivity of electrocatalytic CO2‐to‐CH4. M−C (M=metal) bonds are particularly important for tuning the multi‐electron reaction; however, its construction in nanomaterials is challenging. Here, via rational design of in situ anchoring of Cu SAs (single atoms) on the unique platform graphdiyne, we firstly realize the construction of a chemical bond Cu−C (GDY). In situ Raman spectroelectrochemistry and DFT calculations confirm that due to the fabrication of the Cu−C bond, during CO2 reduction, the formation of *OCHO intermediates is dominant rather than *COOH on Cu atoms, facilitating the formation of CH4. Therefore, we find that constructing the Cu−C bond in Cu SAs/GDY can supply an efficient charge transfer channel, but most importantly control the reaction intermediates and guide a more facile reaction pathway to CH4, thereby significantly boosting its catalytic performance. This work provides new insights on enhancing the selectivity for CO2RR at the atomic level. [ABSTRACT FROM AUTHOR]

Incorporating synthetic macrocycles with unique structures and distinct conformations into conjugated macrocycle polymers (CMPs) can endow the resulting materials with great potentials in gas uptake and pollutant adsorption. Here, four CMPs (CMP‐n, n=1–4) capable of reversibly capturing iodine and efficiently separating carbon dioxide are constructed from per‐triflate functionalized leaning tower[6]arene (LT6‐OTf) and [2]biphenyl‐extended pillar[6]arene (BpP6‐OTf) via Pd‐catalyzed Sonogashira–Hagihara cross‐coupling reaction. Intriguingly, owing to the appropriate cavity size of LT6‐OTf and the numerous aromatic rings in the framework, the newly designed CMP‐4 possesses an outstanding I2 affinity with a large uptake capacity of 208 wt % in vapor and a great removal efficiency of 94 % in aqueous solutions. To our surprise, with no capacity to accommodate nitrogen, CMP‐2 constructed from BpP6‐OTf is able to specifically capture carbon dioxide at ambient conditions. [ABSTRACT FROM AUTHOR]

A new and simple strategy towards electric‐field‐driven multiple chirality switching device has been designed and fabricated by combining a newly synthesized base‐responsive chiroptical polymer switch (R‐FLMA) and p‐benzoquinone (p‐BQ) via proton‐coupled electron transfer (PCET) mechanism. Clear and stable triple chirality states (silence, positive, negative) of this device in visible band can be regulated reversibly (>1000 cycles) by adjusting voltage programs. Furthermore, such chiral switching phenomena are also accompanied by apparent changes of color and fluorescence. More importantly, the potential application of this device for a spatial light modulator has also been demonstrated. [ABSTRACT FROM AUTHOR]

It is common that different crystal facets in metal and metal oxide nanocrystals display different catalytic performances, whereas such phenomena have been rarely documented in metal–organic frameworks (MOFs). Herein, we demonstrate for the first time that a nickel metal–organic layer (MOL) exposing rich (100) crystal facets (Ni‐MOL‐100) shows a much higher photocatalytic CO2‐to‐CO activity than the one exposing rich (010) crystal facets (Ni‐MOL‐010) and its bulky counterpart (bulky Ni‐MOF), with a catalytic activity up to 2.5 and 4.6 times more active than Ni‐MOL‐010 and bulky Ni‐MOF, respectively. Theoretical studies reveal that the two coordinatively unsaturated NiII ions with a close distance of 3.50 Å on the surface of Ni‐MOL‐100 enables synergistic catalysis, leading to more favorable energetics in CO2 reduction than that of Ni‐MOL‐010. [ABSTRACT FROM AUTHOR]

The reaction of precursors containing both nitrogen and oxygen atoms with NiII under 500 °C can generate a N/O mixing coordinated Ni‐N3O single‐atom catalyst (SAC) in which the oxygen atom can be gradually removed under high temperature due to the weaker Ni−O interaction, resulting in a vacancy‐defect Ni‐N3‐V SAC at Ni site under 800 °C. For the reaction of NiII with the precursor simply containing nitrogen atoms, only a no‐vacancy‐defect Ni‐N4 SAC was obtained. Experimental and DFT calculations reveal that the presence of a vacancy‐defect in Ni‐N3‐V SAC can dramatically boost the electrocatalytic activity for CO2 reduction, with extremely high CO2 reduction current density of 65 mA cm−2 and high Faradaic efficiency over 90 % at −0.9 V vs. RHE, as well as a record high turnover frequency of 1.35×105 h−1, much higher than those of Ni‐N4 SAC, and being one of the best reported electrocatalysts for CO2‐to‐CO conversion to date. [ABSTRACT FROM AUTHOR]

There is a demand to develop molecular catalysts promoting the hydrogen evolution reaction (HER) with a high catalytic rate and a high tolerance to various inhibitors, such as CO and O2. Herein we report a cobalt catalyst with a penta‐dentate macrocyclic ligand (1‐Co), which exhibits a fast catalytic rate (TOF=2210 s−1) in aqueous pH 7.0 phosphate buffer solution, in which proton transfer from a dihydrogen phosphate anion (H2PO4−) plays a key role in catalytic enhancement. The electrocatalyst exhibits a high tolerance to inhibitors, displaying over 90 % retention of its activity under either CO or air atmosphere. Its high tolerance to CO is concluded to arise from the kinetically labile character of undesirable CO‐bound species due to the geometrical frustration posed by the ligand, which prevents an ideal trigonal bipyramid being established. [ABSTRACT FROM AUTHOR]

Improving the stability of lead halide perovskite quantum dots (QDs) in a system containing water is the key for their practical application in artificial photosynthesis. Herein, we encapsulate low‐cost CH3NH3PbI3 (MAPbI3) perovskite QDs in the pores of earth‐abundant Fe‐porphyrin based metal organic framework (MOF) PCN‐221(Fex) by a sequential deposition route, to construct a series of composite photocatalysts of MAPbI3@PCN‐221(Fex) (x=0–1). Protected by the MOF the composite photocatalysts exhibit much improved stability in reaction systems containing water. The close contact of QDs to the Fe catalytic site in the MOF, allows the photogenerated electrons in the QDs to transfer rapidly the Fe catalytic sites to enhance the photocatalytic activity for CO2 reduction. Using water as an electron source, MAPbI3@PCN‐221(Fe0.2) exhibits a record‐high total yield of 1559 μmol g−1 for photocatalytic CO2 reduction to CO (34 %) and CH4 (66 %), 38 times higher than that of PCN‐221(Fe0.2) in the absence of perovskite QDs. [ABSTRACT FROM AUTHOR]

The solar‐driven CO2 reduction is a challenge in the field of "artificial photosynthesis", as most catalysts display low activity and selectivity for CO2 reduction in water‐containing reaction systems as a result of competitive proton reduction. Herein, we report a dinuclear heterometallic complex, [CoZn(OH)L1](ClO4)3 (CoZn), which shows extremely high photocatalytic activity and selectivity for CO2 reduction in water/acetonitrile solution. It achieves a selectivity of 98 % for CO2‐to‐CO conversion, with TON and TOF values of 65000 and 1.8 s−1, respectively, 4, 19, and 45‐fold higher than the values of corresponding dinuclear homometallic [CoCo(OH)L1](ClO4)3 (CoCo), [ZnZn(OH)L1](ClO4)3 (ZnZn), and mononuclear [CoL2(CH3CN)](ClO4)2 (Co), respectively, under the same conditions. The increased photocatalytic performance of CoZn is due to the enhanced dinuclear metal synergistic catalysis (DMSC) effect between ZnII and CoII, which dramatically lowers the activation barriers of both transition states of CO2 reduction. In sync with zinc: A dinuclear heterometallic CoZn catalyst shows much higher photocatalytic activity than the corresponding dinuclear homometallic CoCo and ZnZn catalysts, or the mononuclear Co and Zn catalysts for CO2 reduction under the same conditions. The high performance of the CoZn catalyst is due to the enhanced dinuclear metal synergistic catalysis (DMSC) effect between ZnII and CoII. [ABSTRACT FROM AUTHOR]

The removal of C2H2 and C2H6 from C2H4 streams is of great significance for feedstock purification to produce polyethylene and other commodity chemicals but the simultaneous adsorption of C2H6 and C2H2 over C2H4 from a ternary mixture has never been realized. Herein, a robust metal–organic framework, TJT‐100, was designed and synthesized, which demonstrates remarkably selective adsorption of C2H2 and C2H6 over C2H4. Breakthrough experiments show that TJT‐100 can be used as an adsorbent for high‐performance purification of C2H4 from a ternary mixture of C2H2/C2H4/C2H6 (0.5:99:0.5) to afford a C2H4 purity greater than 99.997 %, beyond that required for ethylene polymerization. Computational studies reveal that the uncoordinated carboxylate oxygen atoms and coordinated water molecules pointing towards the pore can trap C2H2 and C2H6 through the formation of multiple C−H⋅⋅⋅O electrostatic interactions, while the corresponding C2H4–framework interaction is unfavorable. A robust porous metal–organic framework was synthesized and utilized for the highly selective separation of C2H4 from a ternary mixture of C2 hydrocarbons. After a single operation, the C2H4 purity of the outlet was greater than 99.997 %. [ABSTRACT FROM AUTHOR]

A dinuclear cobalt complex [Co2(OH)L1](ClO4)3 ( 1, L1=N[(CH2)2NHCH2( m-C6H4)CH2NH(CH2)2]3N) displays high selectivity and efficiency for the photocatalytic reduction of CO2 to CO in CH3CN/H2O (v/v=4:1) under a 450 nm LED light irradiation, with a light intensity of 100 mW cm−2. The selectivity reaches as high as 98 %, and the turnover numbers (TON) and turnover frequencies (TOF) reach as high as 16896 and 0.47 s−1, respectively, with the calculated quantum yield of 0.04 %. Such high activity can be attributed to the synergistic catalysis effect between two CoII ions within 1, which is strongly supported by the results of control experiments and DFT calculations. [ABSTRACT FROM AUTHOR]