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The electrochemical CO 2 reduction to high-value-added chemicals is one of the most promising and challenging research in the energy conversion field. An efficient ECR catalyst based on a Cu-based conductive metal-organic framework (Cu-DBC) is dedicated to producing CH 4 with superior activity and selectivity, showing a Faradaic efficiency of CH 4 as high as ~80% and a large current density of −203 mA cm −2 at −0.9 V vs. RHE. The further investigation based on theoretical calculations and experimental results indicates the Cu-DBC with oxygen-coordinated Cu sites exhibits higher selectivity and activity over the other two crystalline ECR catalysts with nitrogen-coordinated Cu sites due to the lower energy barriers of Cu-O 4 sites during ECR process. This work unravels the strong dependence of ECR selectivity on the Cu site coordination environment in crystalline porous catalysts, and provides a platform for constructing highly selective ECR catalysts. Crystalline porous catalysts with single Cu sites are dedicated to exploring the dependence of CO 2 electroreduction selectivity on the coordination environment of catalytic sites. The conductive MOF Cu-DBC with oxygen-coordinated Cu sites shows a high Faradaic efficiency ~80% of CO 2 -to-CH 4 .

Photocatalytic CO 2 reduction reaction has been developed as an effective strategy to convert CO 2 into reusable chemicals. However, the reduction products of this reaction are often of low utilization value. Herein, we effectively connect photocatalytic CO 2 reduction and amino carbonylation reactions in series to reconvert inexpensive photoreduction product CO into value-added and easily isolated fine chemicals. In this tandem transformation system, we synthesize an efficient photocatalyst, NNU-55-Ni, which is transformed into nanosheets (NNU-55-Ni-NS) in situ to improve the photocatalytic CO 2 -to-CO activity significantly. After that, CO serving as reactant is further reconverted into organic molecules through the coupled carbonylation reactions. Especially in the carbonylation reaction of diethyltoluamide synthesis, CO conversion reaches up to 85%. Meanwhile, this tandem transformation also provides a simple and low-cost method for the 13 C isotopically labeled organic molecules. This work represents an important and feasible pathway for the subsequent separation and application of CO 2 photoreduction product. A Ni-based MOF catalyst is reported to facilitate the photocatalytic reduction of CO2 to CO, a low-value product. In tandem, the as-produced CO is used as a reactant in the Pd-catalyzed carbonylation of aryl halides and other fine organic chemicals.

Electrochemical water splitting is one of the most economical and sustainable methods for large-scale hydrogen production. However, the development of low-cost and earth-abundant non-noble-metal catalysts for the hydrogen evolution reaction remains a challenge. Here we report a two-dimensional coupled hybrid of molybdenum carbide and reduced graphene oxide with a ternary polyoxometalate-polypyrrole/reduced graphene oxide nanocomposite as a precursor. The hybrid exhibits outstanding electrocatalytic activity for the hydrogen evolution reaction and excellent stability in acidic media, which is, to the best of our knowledge, the best among these reported non-noble-metal catalysts. Theoretical calculations on the basis of density functional theory reveal that the active sites for hydrogen evolution stem from the pyridinic nitrogens, as well as the carbon atoms, in the graphene. In a proof-of-concept trial, an electrocatalyst for hydrogen evolution is fabricated, which may open new avenues for the design of nanomaterials utilizing POMs/conducting polymer/reduced-graphene oxide nanocomposites. The development of low-cost and earth-abundant non-noble-metal catalysts for the hydrogen evolution reaction remains a challenge. Here, the authors report and evaluate a catalyst based on a two-dimensional coupled hybrid of molybdenum carbide and reduced graphene oxide.

In modern industries, the aerobic oxidation of C(sp 3 )-H bonds to achieve the value-added conversion of hydrocarbons requires high temperatures and pressures, which significantly increases energy consumption and capital investment. The development of a light-driven strategy, even under natural sunlight and ambient air, is therefore of great significance. Here we develop a series of hetero-motif molecular junction photocatalysts containing two bifunctional motifs. With these materials, the reduction of O 2 and oxidation of C(sp 3 )-H bonds can be effectively accomplished, thus realizing efficient aerobic oxidation of C(sp 3 )-H bonds in e.g., toluene and ethylbenzene. Especially for ethylbenzene oxidation reactions, excellent catalytic capacity (861 mmol g cat −1 ) is observed. In addition to the direct oxidation of C(sp 3 )-H bonds, CeBTTD-A can also be applied to other types of aerobic oxidation reactions highlighting their potential for industrial applications. The authors report a family of photocatalysts containing Ce active sites and perylene diimide ligands for the aerobic oxidation of substituted toluene, ethylbenzene, benzyl alcohol, thioanisole, and benzylamine in acetonitrile.

Rational design of robust photocatalytic systems to direct capture and in-situ convert diluted CO 2 from flue gas is a promising but challenging way to achieve carbon neutrality. Here, we report a new type of host-guest photocatalysts by integrating CO 2 -enriching ionic liquids and photoactive metal-organic frameworks PCN-250-Fe 2 M (M = Fe, Co, Ni, Zn, Mn) for artificial photosynthetic diluted CO 2 reduction in gas-solid phase. As a result, [Emim]BF 4 (39.3 wt%)@PCN-250-Fe 2 Co exhibits a record high CO 2 -to-CO reduction rate of 313.34 μmol g −1 h −1 under pure CO 2 atmosphere and 153.42 μmol g −1 h −1 under diluted CO 2 (15%) with about 100% selectivity. In scaled-up experiments with 1.0 g catalyst and natural sunlight irradiation, the concentration of pure and diluted CO 2 (15%) could be significantly decreased to below 85% and 10%, respectively, indicating its industrial application potential. Further experiments and theoretical calculations reveal that ionic liquids not only benefit CO 2 enrichment, but also form synergistic effect with Co 2+ sites in PCN-250-Fe 2 Co, resulting in a significant reduction in Gibbs energy barrier during the rate-determining step of CO 2 -to-CO conversion. Artificial photosynthetic diluted CO 2 reduction from fuel gas is promising but challenging for carbon neutrality. Here, the authors report a host-guest system by integrating CO 2 -enriching ionic liquids and photoactive metal-organic frameworks, greatly enhancing CO 2 -to-CO conversion efficiency.

Constructing redox semiconductor heterojunction photocatalysts is the most effective and important means to complete the artificial photosynthetic overall reaction (i.e., coupling CO₂ photoreduction and water photo-oxidation reactions). However, multiphase hybridization essence and inhomogeneous junction distribution in these catalysts extremely limit the diverse design and regulation of the modes of photogenerated charge separation and transfer pathways, which are crucial factors to improve photocatalytic performance. Here, we develop molecular oxidation—reduction (OR) junctions assembled with oxidative cluster (PMo12, for water oxidation) and reductive cluster (Ni₅, for CO₂ reduction) in a direct (d-OR), alternant (a-OR), or symmetric (s-OR) manner, respectively, for artificial photosynthesis. Significantly, the transfer direction and path of photogenerated charges between traditional junctions are obviously reformed and enriched in these well-defined crystalline catalysts with monophase periodic distribution and thus improve the separation efficiency of the electrons and holes. In particular, the charge migration in s-OR shows a periodically and continuously opposite mode. It can inhibit the photogenerated charge recombination more effectively and enhance the photocatalytic performance largely when compared with the traditional heterojunction models. Structural analysis and density functional theory calculations disclose that, through adjusting the spatial arrangement of oxidation and reduction clusters, the energy level and population of the orbitals of these OR junctions can be regulated synchronously to further optimize photocatalytic performance. The establishment of molecular OR junctions is a pioneering important discovery for extremely improving the utilization efficiency of photogenerated charges in the artificial photosynthesis overall reaction.

The semi‐hydrogenation of alkyne to form Z‐olefins with high conversion and high selectivity is still a huge challenge in the chemical industry. Moreover, flammable and explosive hydrogen as the common hydrogen source of this reaction increases the cost and danger of industrial production. Herein, we connect the photocatalytic hydrogen evolution reaction and the semi‐hydrogenation reaction of alkynes in series and successfully realize the high selective production of Z‐alkenes using low‐cost, safe, and green water as the proton source. Before the cascade reaction, a series of isomorphic metal–organic cage catalysts (CoxZn8−xL6, x = 0, 3, 4, 5, and 8) are designed and synthesized to improve the yield of the photocatalytic hydrogen production. Among them, Co5Zn3L6 shows the highest photocatalytic activity, with a H2 generation rate of 8.81 mmol g−1 h−1. Then, Co5Zn3L6 is further applied in the above tandem reaction to efficiently reduce alkynes to Z‐alkenes under ambient conditions, which can reach high conversion of >98% and high selectivity of >99%, and maintain original catalytic activity after multiple cycles. This “one‐pot” tandem reaction can achieve a highly selective and safe stepwise conversion from water into hydrogen into Z‐olefins under mild reaction conditions. A series of isostructural stable metal–organic cages (CoxZn8−xL6, x = 0, 3, 4, 5, and 8) are constructed to catalyze the hydrogen evolution reaction. Significantly, Co5Zn3L6 with the highest H2 generation rate (8.81 mmol g−1 h−1) is further applied in photocatalytic alkyne semi‐hydrogenation using H2O as a proton source, which can yield high conversion (98%) and high Z‐olefin selectivity (99%) under mild conditions.

It is well known that the low-valent Cu species are important catalytically active centers in the reduction of CO 2 to hydrocarbon products. However, the Cu(I)-based catalysts are easily reduced during the electroreduction of CO 2 , which causes phase transformation of catalysts and leads to a decrease of intrinsic catalytic activity. Therefore, it is of great significance to synthesize Cu(I)-based catalysts with specific interactions that can keep the catalytically active Cu sites stable in the electrocatalytic process. Based on the above considerations, a hexanuclear Cu cluster with strong cuprophilic interactions has been designed and utilized as a secondary building unit (SBU) to construct a stable metal-organic framework (MOF) electrocatalyst (NNU-50). As expected, the NNU-50 has served as an effective electrocatalyst for the CO 2 -to-CH 4 conversion by exhibiting a high Faradaic efficiency for CH 4 ( FE CH 4 ) of 66.40% and a large current density of ∼ 400 mA·cm −2 at −1.0 V vs. reversible hydrogen electrode (RHE), which is one of the best catalytic performances among the stable MOF electrocatalysts until now. This work contributes more ideas for the design of stable and efficient MOF-based electrocatalysts for CO 2 reduction reaction.

Low-selective CO2 photoreduction systems are often overlooked in research, because the resulting mixed products are difficult to use in further reactions. In particular, the reutilization of gaseous hybrid products (such as CO and H2), which are often mixed with incompletely converted CO2, is difficult. Here we design and construct two highly active cluster-based catalysts, Ni5W10 and Ni6W10, which can be utilized in an efficient triple tandem reaction composed of low-selective CO2 photoreduction, alkyne semi-hydrogenation and carbonylation reactions. The triple tandem system can sequentially convert the H2 and CO mixture into high-value olefins and carbonyls, with an atomic utilization efficiency of up to 94%. In situ one-pot coupling of low-selective CO2 photoreduction with alkyne semi-hydrogenation promotes the overall photoconversion efficiency (up to 1,425.0 μmol g−1 h−1), CO selectivity (from 50.8% to 80.0%) and alkyne-to-olefin transformation (conversion >86.0%, selectivity ~100.0%). Subsequently, the purified CO can be converted to different types of carbonylated product (CO conversion between 51% and 99%).Low-selectivity photocatalytic carbon dioxide reduction has been overlooked, due to the difficulty in separating and utilizing the mixed products. Now, a triple tandem strategy is reported to convert the mixed reduction products, H2 and CO, sequentially into olefinic and carbonyl fine compounds with high atom utilization efficiency.

Rational design of robust photocatalytic systems to direct capture and in-situ convert diluted CO from flue gas is a promising but challenging way to achieve carbon neutrality. Here, we report a new type of host-guest photocatalysts by integrating CO -enriching ionic liquids and photoactive metal-organic frameworks PCN-250-Fe M (M = Fe, Co, Ni, Zn, Mn) for artificial photosynthetic diluted CO reduction in gas-solid phase. As a result, [Emim]BF (39.3 wt%)@PCN-250-Fe Co exhibits a record high CO -to-CO reduction rate of 313.34 μmol g h under pure CO atmosphere and 153.42 μmol g h under diluted CO (15%) with about 100% selectivity. In scaled-up experiments with 1.0 g catalyst and natural sunlight irradiation, the concentration of pure and diluted CO (15%) could be significantly decreased to below 85% and 10%, respectively, indicating its industrial application potential. Further experiments and theoretical calculations reveal that ionic liquids not only benefit CO enrichment, but also form synergistic effect with Co sites in PCN-250-Fe Co, resulting in a significant reduction in Gibbs energy barrier during the rate-determining step of CO -to-CO conversion.