Hydroformylation of alkenes with syngas is among the most atom-economical industrial catalytic processes. While porous organophosphine polymer-immobilized rhodium catalysts have been extensively investigated for hydroformylation, the fabrication of such polymers generally demands pre-functionalization of phosphine monomers, which entails tedious and multi-step synthetic procedures. Herein, we report a facile one-pot Friedel-Crafts polymerization strategy to construct a series of fluorinated phosphine-containing polymers (FPPs)-supported single-atom Rh catalysts using tris(triphenylphosphine)chlororhodium and 2,3,5,6-tetrafluoro-1,4-benzenedimethanol as monomers. Incorporation of a rigid polycyclic comonomer enables precise modulation of the coordination microenvironment surrounding RhP active sites, generating electron-rich Rh species that strengthen CO adsorption and accelerate CC coupling with alkyl intermediates, thereby markedly boosting catalytic activity. The optimal catalyst denoted FPPs-SBF-Rh-3 delivers prominent catalytic efficiency in hydroformylation with either CO or CO2 serving as the carbonylation feedstock. This study establishes a straightforward modular route toward high-performance Rh-based hydroformylation catalysts and sheds light on the rational design of heterogeneous single-atom catalysts for future catalytic applications.

Acetic acid (AA) has a growing market with wide applications within the food industry and chemical intermediates. Conventional AA production processes rely heavily on fossil-based feedstocks and noble metal catalysts, resulting in high energy consumption and cost with poor environmental sustainability. Synthesis of AA using CO2 is of great importance and presents a promising avenue for addressing environmental challenges and advancing sustainable energy solutions. In this short review, we systematically summarize and discuss the development of AA synthesis from CO2 since the 1990s, and we manage to provide an in-depth analysis of the recent evolutions and corresponding catalytic systems for AA production from CO2. The review scrutinizes three ways (four routes) for the conversion of CO2 to AA, catalytic systems and reaction mechanisms, and offers a future direction for harnessing CO2 conversion to AA. Readers can acquire a thorough grasp of AA synthesis from CO2, revealing its promise as a sustainable route for chemical synthesis.

Solar-driven conversion of abundant small molecules such as H2O, CO2 and N2 into value-added chemicals represents an attractive strategy for sustainable energy utilization and green manufacturing. Integrating microorganisms with functional materials has emerged as a powerful route to the utilization and conversion of solar power by combining the efficient photoelectric properties and microenvironment regulation ability of artificial materials with the catalytic specificity, self-repair capability, and metabolic versatility of living cells. In this review, we first discuss the conceptual background and significance of photosynthetic biohybrid systems. We then summarize the components of such microorganism-material biohybrids. Next, we analyze interface engineering strategies and electron transfer pathways in the biohybrid systems, with emphasis on surface integration, intracellular integration, and periplasmic integration of functional materials with microorganisms. We further review recent advances in chemical production through these biohybrids from three perspectives: hydrogen production, carbon-based chemical synthesis from CO2, and nitrogen-containing compound synthesis from N2. Finally, we highlight the remaining challenges and emerging opportunities in photosynthetic biohybrid systems and discuss its prospects as a next-generation platform for sustainable solar-to-chemical biomanufacturing.

Development of efficient and stable metal catalysts for the selective aqueous phase hydrodeoxygenation (HDO) of biomass-derived oxygenates to value-added biofuels is highly desired. An innovative surface microenvironment modulation strategy was used to construct the nitrogen-doped hollow carbon sphere encapsulated with Pd (Pd@NHCS-X, X: 600-800) nanoreactors for catalytic HDO of biomass-derived vanillin in water. The specific surface microenvironments of Pd@NHCS catalysts including the electronic property of active Pd centers and the surface wettability and porous structure of NHCS supports could be well-controlled by the calcination temperature of catalysts. Intrinsic kinetic evaluations demonstrated that the Pd@NHCS-600 catalyst presented a high turnover frequency of 337.77 h-1 and a low apparent activation energy of 18.63 kJ/mol. The excellent catalytic HDO performance was attributed to the unique surface microenvironment of Pd@NHCS catalyst based on structure-performance relationship analysis and DFT calculations. It revealed that pyridinic N species dominated the electronic property regulation of Pd sites through electronic metal-support interaction (EMSI) and produced numerous electron-rich active Pd centers, which not only intensified the dissociation and activation of H2 molecules, but also substantially improved the activation capability of vanillin via the enhanced adsorption of -C=O group. The fine hydrophilicity and abundant porous structure promoted the uniform dispersion of catalyst and ensured the effective access of reactants to catalytic active centers in water. Additionally, the Pd@NHCS-600 catalyst exhibited excellent catalytic stability and broad substrate applicability for the selective aqueous phase HDO of various biomass-derived carbonyl compounds. The proposed surface microenvironment modulation strategy will provide a new consideration for the rational design of high- performance nitrogen-doped carbon-supported metal catalysts for catalytic biomass transformation. Published by Elsevier B.V. All rights reserved.

Olefin hydroformylation is one of the most important industrial processes for aldehyde synthesis. Heterogeneous catalysts are easy to separate compared with homogeneous catalysts, yet with limited success in activity and regioselectivity control. In the present work, a zeolite-encapsulated rhodium carbide species (RhCx@S-1) catalyst was developed, demonstrating not only relatively high catalytic activity but also good regioselectivity and stability in heterogeneous hydroformylation. The unique microenvironment of rhodium carbide species was formed in situ during the catalyst carbonization reduction process, tuning the steric and electronic characteristics of Rh species to obtain more linear aldehydes. This work shows an alternative strategy to promote the regioselectivity of olefin hydroformylation catalyzed by zeolite-confined catalysts and provides insights into the selective regulation of heterogeneous catalysts.

CO2 hydrogenation to C2+OH is highly attractive but remains a great challenge due to low C2+OH productivity and poor catalyst stability. Herein, we report efficient CO2 hydrogenation to C2+OH over a Ni- and K-co-modified Fe-based catalyst (1Ni-4K/Fe), achieving a promising space-time yield (STY) of 317.0 mg/g/h and catalytic stability over 300 h. Systematic investigations reveal that the addition of Ni promotes the formation of surface alkyl intermediates, while K mitigates the undesired deep hydrogenation of these alkyl intermediates. Both effects facilitate coupling between *CO and *CHx, thereby enhancing the production of C2+OH. Moreover, the synergistic effect between K and Ni expedites the formation of Fe5C2 and the recarburization of in situ oxidized Fe species during the reaction, resulting in enhanced stability of the 1Ni-4K/Fe catalyst. Additionally, by introduction of Rh-1/POP (for the hydroformylation of olefins to aldehydes) and Cu@SiO2 (for the hydrogenation of aldehydes to alcohols) catalysts to establish a 1Ni-4K/Fe||Rh-1/POPs||Cu@SiO2 triple-tandem system, an excellent C2+OH STY of 980.5 mg/g/h can be achieved, along with a C2+OH selectivity of 55.0% and a high proportion of C3+OH (75.6%) in the alcohol products.

Cu catalysts with different compositions and different Cu and promoter contents were prepared by precipitation-gel method and studied for the selective hydrogenation of syngas or biomass-based diethyl malonate (DEM) to valuable 1,3-propanediol (1,3-PDO). The Ga-promoted 70Cu6Ga/SiO2 catalyst was found to exhibit the highest catalytic performance, achieving 100 % DEM conversion and 76.6 % 1,3-PDO selectivity under reaction conditions of 160 °C and 8 MPa H2. The 70Cu6Ga/SiO2 bimetallic catalyst also presented obviously better stability than that of the monometallic 70Cu/SiO2 catalyst in a continuous flow reactor over 180 h time-on stream. Characterization results showed that the incorporation of Ga increased the interaction between Cu and Ga species, hindered the full reduction of Cu2+ species, and thus increased the proportion of Cu+ and the number of Lewis acidic sites on the catalyst surface. The synergistic effect between Cu0 and Cu+ enhanced the adsorption and activation of ester carbonyl groups and their subsequent hydrogenation, eventually contributed to the outstanding performances of the CuGa/SiO2 bimetallic catalysts.

Coupling of CO2 with biomass-derived molecules into degradable plastic monomer provides a promising strategy to address the increasing problems of carbon recycle and carbon neutrality. Herein, we develop a sustainable route to produce 6-hydroxycaproate (6-HMC) by coupling photocatalytic carboxylation of biomass-derived furfuryl alcohol with CO2 to 2-furanacetic acid (FA), and the thermocatalytic hydrogenolysis of methyl 2-tetrahydrofuranyl acetate (MTFA) derived from FA, wherein Pd/CeO2 exhibit the highest productivity of 6-HMC (505 mmol(6-HMC) mmol(metal)(-1) h(-1)), much higher than its counterparts of precious- and non-precious-metal catalysts. Moreover, Pd/CeO2 also presents good stability for 6 recycles without remarkable decrease in 6-HMC yield. Systematic experiments and computational studies suggest that higher concentration of oxygen vacancies and strong metal-support interactions account for enhanced catalytic performance of Pd/CeO2. The work employs CO2 and lignocellulosic-derived platform molecule as feedstocks to produce valuable degradable plastic monomer, providing a promising route to access pure-CO2 originated high-carbon oxygen-containing compounds.

We demonstrate a mechanism that achieves alkyl C-O bond cleavage on transition metal (TM) catalysts by overcoming a transition state involving a partially activated C-H bond and an O-TM bond. C-H binds with TMs through a-agostic or agostic-like interactions, hence the notable elongation of the C-H bond length. Upon the cleavage of the C-O bond, the C-H bond is restored. Using tetrahydrofurfuryl alcohol (THFA) as a probe molecule, we were able to regulate the selectivity of THFA ring opening by tuning the oxophilicity of TMs for MoS2-supported dual -metal catalysts, which in turn affected the reaction mechanism of C-O bond cleavage, being either the partial C-H-activation-assisted or the oxygen -bonded mechanism. We validated the partial C-H-activation-assisted mechanism for the C-O bond cleavage of methanol on dual -metal catalysts, on the basis of which we established that the transition -state energy is contributed by the C-H/TM and O/TM interactions.

We report a strategy of catalyst design to modulate oxygen vacancies through the control of Au/ceria interface structures, promoting Au activity for carbon monoxide production in carbon dioxide electroreduction.

Solvent effects add a new dimension for tuning the activity and selectivity of heterogeneous catalytic reactions, which is extensively employed in the hydrogenation of unsaturated compounds with multiple functional groups. In this concept, we briefly summarize recent developments on how the solvent effects affect the catalytic performance from the following aspects: 1) the polarity of the solvent can influence the interaction between the solvent and the reactant or intermediate; 2) the composition of mixed solvent can influence the reactivity of the reactant or intermediate; 3) solvent effect varies with the metal identity and support; 4) the solvent can induce surface modification of the supported catalysts. This summarization will provide insights into the rational development of efficient and selective heterogeneous hydrogenation catalytic system to realize the precise synthesis of desired chemicals. Solvent effects provide numerous opportunities for tuning the activity and selectivity of heterogeneous catalytic reactions. This concept briefly summarizes recent developments on how the solvent effects affect the catalytic performance from solvent polarity, solvent composition, and the interaction between the solvent, reactant and catalysts. image

The development of effective and stable non-precious catalysts for hydrogenation of ester to diols remains a challenge. Herein, the catalytic hydrogenation of ethyl lactate (EL) to 1,2-propanediol (1,2-PDO) with supported Co catalysts derived from layered double hydroxides (LDHs) is investigated. Catalytic tests reveal that LDH-derived Co catalysts exhibit the best catalytic performance with 98 % of EL conversion and >99 % of 1,2-PDO selectivity at mild conditions, compared with other Co catalysts (supported on Al2O3, and TiO2) and LDH-derived Cu catalysts. Due to the strong interaction among Co and Al matrix, the main composition is metallic Co0 and CoO after reduction at 600 °C. Besides, the catalyst shows good recyclability in the liquid phase hydrogenation. The superior catalytic performance can be attributed to the synergistic effect between Co0 and CoO, in which H2 molecule is activated on Co0 and EL is strongly adsorbed on CoO via hydroxyl groups.

Selective activation of C-O bond is of fundamental importance in the precise conversion of oxygenates into value-added compounds in an atom-economic and sustainable manner, and meanwhile, the structurally well-defined dual-atoms catalysts (DACs) have been scarcely investigated in this field. In this study, a series of transition metal DACs anchored on nitrogen-doped graphene (TM 2 /NC, TM= Pt, Ir, Rh, Pd, Ru, Co, Ni and Cu) was constructed to make a comprehensive investigation of their selectivity in the hydrogenative transformation of furfuryl alcohol (FAL), an important biomass platform molecule, to 1,2-pentanediol (1,2-PeD) via selective cleavage of furanic C5-O bond, by density functional theory (DFT) calculations and microkinetic modeling. We found that Ir 2 /NC demonstrated a high selectivity for the cleavage of furanic C5-O bond to produce 1,2-PeD, while the production of THFAL or 1,5-pentanediol (1,5-PeD) on other TM 2 /NC catalysts are more favorable. Furthermore, we found that the selective C-O bond cleavage of FAL furan ring is affected by the orbital overlap between the d -orbitals of the anchored metal atoms and the p-orbitals of the adsorbed C atom in FAL, suggesting that the selectivity of the C-O bond cleavage is inextricably related with the electronic property of the anchored metals.

As a typical atomically dispersed catalyst, single -atom catalysts (SACs) aroused enormous research interest in heterogeneous catalysis. In recent years, by incorporating one or several metal atom(s) into the first and/or outer coordination shells of single atoms, the structure of metal has evolved to densely populated single atoms, dual -metal pairs, and multi-atom ensembles. The inter-site or inter-atom synergetic interactions between adjacent metal atoms in these structures boost the adsorption and activation of reactants, potentially leading to improved catalytic performances as compared with corresponding SACs. This perspective highlights the structural advantages of densely populated single atoms, dual -metal pairs, and multi-atom ensembles using many of the successful examples, aiming to shed light on the design of novel catalysts at atomic level.

Valeric ester has been recognized as a new generation of biofuels with promising environmental advantages. Metal-zeolite bifunctional catalysts demonstrated outstanding performance in tandem transformation including the tandem conversion of levulinic acid to valeric ester via synergetic catalysis of C = C bond hydrogenation and C-O bond cleavage, but still suffering from rapid catalyst deactivation due to coke formation. Herein, a hierarchical HZSM-5 supported Ni catalyst was developed, and displayed efficient ethyl valerate production activity with a catalytic lifetime as long as 180 h, which is 8-fold longer than that of microporous zeolite counterpart (20 h). Notably, this nonprecious Ni catalyst can be stably regenerated by calcination at least four times with its total lifetime up to 900 h. Systematic investigations reveal that the presence of secondary porosity, the less strong acid sites and weaker adsorption of ethyl valerate on hierarchical catalysts could effectively alleviate coke formation and promote catalyst stability. More importantly, the hierarchical porosity of HZSM-5 alters the acid site distribution, enabling more acid sites to be located on the external surface, and thus retards the coverage of the active site by carbonaceous species. Besides, the addition of 10 % ethyl valerate in diesel can reduce the emission of exhaust pollutants, wherein the CO, NOx, HC, and soot emissions can be reduced by 13 %, 5 %, 4 %, and 27 % at an engine speed of 1500 rpm, respectively. This work develops an alternative strategy by tuning pore size and acid distribution to enhance the metal/zeolites catalyst stability against coke deposits and promotes the practical application of ethyl valerate as an environmentally friendly oxygenated additive for the current liquid fuels.

AbstractRegulating interfacial electronic structure of oxide-metal composite catalyst for the selective transformation of biomass or plastic waste into high-value chemicals through specific C–O bond scission is still challenging due to the presence of multiple reducible bonds and low catalytic activity. Herein, we find that the inverse catalyst of 4CeOx/Ni can efficiently transform various lignocellulose derivatives and polyether into the corresponding value-added hydroxyl-containing chemicals with activity enhancement (up to 36.5-fold increase in rate) compared to the conventional metal/oxide supported catalyst. In situ experiments and theoretical calculations reveal the electron-rich interfacial Ce and Ni species are responsible for the selective adsorption of C–O bond and efficient generation of Hδ− species, respectively, which synergistic facilitate cleavage of C–O bond and subsequent hydrogenation. This work advances the fundamental understanding of interfacial electronic interaction over inverse catalyst and provides a promising catalyst design strategy for efficient transformation of C–O bond.

The increasingly environmental pollution have drawn global attentions to the development of new techniques that can effectively deal with the pollutants. With the unique set of electronic properties and structural diversities, N-heterocyclic carbenes (NHCs) and related materials are emerging as potential adsorbing materials for adsorptive decontamination of various pollutant-containing mediums. Recent investigations have revealed the feasibility of molecular and heterogeneous NHCs for adsorptive separation of harmful gases including CO2, CO, NOx, SO2, etc. Rather than simple gas trapping, NHCs functions as effective catalytic centers that activating and transforming the captured gas molecules. Besides, heterogeneous NHCs and their complexes have been applied to adsorptive removal of various organic pollutants and heavy metal ions from water solution with high efficiencies. These advancements have illustrated the significant potential of NHCs and their related materials in environmental decontamination. Instead of the well-known catalytic applications of NHCs in organic transformations, this review aims to offer an overview of the emerging applications of NHCs in the field of environmental decontamination and provide a comprehensive understanding of the mechanisms behind the N-heterocyclic carbene material-mediated environmental decontamination processes. With this in mind, the structure, synthesis, application, and performance of NHCs and related materials in environmental processes including gas separation and wastewater treatment are summarized, and the structure-activity relationship is discussed. Besides, the current challenge and future development of NHC-mediated environmental treatments are proposed. This review is expected to serve as a preliminary database for the environmental applications of NHC and related materials and offer deep insights into the rational design of novel NHC-based environmental materials for greener and efficient environmental processes.

Biomass has attracted great attention as a carbon source for the production of valuable chemicals and fuels. Selective ring-opening hydrogenation of cyclic oxygenates derived from biomass offers promising approaches for catalytic synthesis of value-added oxygen-containing compounds compared to corresponding fossil-based protocols. Different catalytic sites are required to perform distinct types of elementary reaction steps (e.g., adsorption and activation of oxygen-containing groups, association of a hydrogen molecule), and thus the synergistic effect of these sites plays a critical role in the selective hydrogenation transformation, which has attracted increasing attention in recent years. Here, we present a review of the ring-opening hydrogenation of the representative platforms of furfural, 5-hydroxymethylfurfural, gamma-valerolactone, triacetic acid lactone, and their derivatives catalyzed by various homogeneous and heterogeneous catalysts. The particular focus is placed on the synergistic effect of the active sites, including Bronsted acid, Lewis acid, base, and metallic sites, on the selective scission of two different cyclic C-O bonds and related hydrogenation transformation. The reaction mechanism is also discussed to provide insights for guiding the design of multifunctional catalysts for biomass valorization. Finally, the current challenges and future opportunities in the synergistic catalytic ring-opening transformation of biomass-derived cyclic compounds are also analyzed.

Ni-based catalysts have been widely studied in the hydrogenation of CO2 to CH4, but selective and efficient synthesis of higher alcohols (C-2+OH) from CO2 hydrogenation over Ni-based catalyst is still challenging due to successive hydrogenation of C1 intermediates leading to methanation. Herein, we report an unprecedented synthesis of C2+OH from CO2 hydrogenation over K-modified Ni-Zn bimetal catalyst with promising activity and selectivity. Systematic experiments (including XRD, in situ spectroscopic characterization) and computational studies reveal the in situ generation of an active K-modified Ni-Zn carbide (K-Ni(3)Zn(1)C(0.)7) by carburization of Zn-incorporated Ni-0, which can significantly enhance CO(2 )adsorption and the surface coverage of alkyl intermediates, and boost the C-C coupling to C2+OH rather than conventional CH4. This work opens a new catalytic avenue toward CO2 hydrogenation to C2+OH, and also provides an insightful example for the rational design of selective and efficient Ni-based catalysts for CO2 hydrogenation to multiple carbon products.

Metal-organic framework (MOF) based single-atom catalysts (SACs) with distinctive features are emerging extraordinary materials in the electrochemical field in the latest years. MOF has the virtues of functional tunability, high surface areas, and well-defined pores structures, while SAC possesses the advantages of maximum atom utilization, special electronic characteristics, and quantum size effects. By combining the merits of both, MOF-based SACs exhibit huge potential in electrocatalytic CO2 reduction reactions (CO2RR) and, more generally, in the field of electroreduction reactions. In this review, the diverse fabrication strategies and principles of MOF-based SACs, including MOF-immobilized SACs and MOF-derived SACs, and the corresponding representative samples of each strategy are systematically introduced and summarized. Then, insights into the mechanisms and pathways of electrochemical CO2RR are discussed. In addition, we illustrate elaborately the recent progress of MOF-derived SACs for electrocatalytic CO2RR to valuable chemicals/fuels according to the classification of catalytic products, C1, C2, and C2+ species. At last, the current challenges and future development directions of MOF-based SACs toward electrochemical CO2RR are proposed. We hope that this review would be helpful in rational designing MOF-based SACs with higher efficiency, selectivity, and long-term durability for the electrocatalytic CO2RR and/or a wider range of electrochemical applications in the future.