Facing soaring global energy demand and intensifying environmental problems, the search for sustainable energy alternatives has become imperative. The efficient conversion of carbon dioxide (CO₂), one of the primary greenhouse gases, plays the crucial role in mitigating global climate change. The electrocatalytic CO₂ reduction reaction (eCO₂RR) provides an effective solution for its conversion into high-value-added chemicals, promoting the development of the carbon cycle and green chemistry. Porous materials of distinctive physicochemical properties have demonstrated substantial potential in eCO₂RR. In this review, various strategies of porousizing catalysts for boosted eCO₂RR are briefly summarized. Subsequently, the functionalities of porous materials including enrichment effect, modulating microenvironmental pH, stabilizing key species, facilitating mass transfer and tuning the nature of active sites to improve the efficiency and selectivity of eCO₂RR are categorized. Furthermore, we discuss the principal challenges confronting current electrocatalytic systems and propose future research directions. Insights from this review are expected to benefit broad communities of chemical and material research for rationalizing porous electrocatalysts and optimizing eCO₂RR performances.

Water splitting powered by clean electricity is a sustainable and promising approach to produce green hydrogen. Currently, noble metal (e.g. Iridium, Ruthenium, Platinum)-based catalysts are most widely used for water splitting electrolysis. However, noble metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity and poor durability. The emergence of metal-organic framework nanosheets (MOFNSs) attracts significant attention due to their unique advantages. Here, a concise, yet comprehensive and critical, review of recent advances in the field of MOFNSs is provided. This review explains the fundamental oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic mechanisms as well as key characterization techniques for the structure-activity relationship study are discussed. Moreover, it discusses efficient design strategies and the brief research advances of MOFNSs in HER, OER, and bifunctional electrocatalysis, along with some challenges and opportunities.

A novel strategy for site-selective benzylic C-H oxidation has been developed through mediated electrolysis. A bulky maleimide N-oxyl radical (MINO) generated by proton-coupled electrochemical oxidation of N-hydroxymaleimide (NHMI), serves as a hydrogen atom-transfer mediator. Good-to-excellent site selectivity was observed among different substrates, providing a practical approach for site-selective benzylic C-H oxidation. Additionally, the hydrogen-atom transfer mechanism for C-H electrochemical oxidation allows the oxidation to proceed at much lower anode potentials relative to direct electrolysis and with minimal reliance on the substrate's electronic properties.

Selective photocatalytic aerobic oxidation of methane to value-added chemicals offers a promising pathway for sustainable chemical industry, yet remains a huge challenge owing to the consecutive overoxidation of primary products. Here, a type II heterojunction were constructed in Ag-AgBr/ZnO to reduce the oxidation potential of stimulated holes and prevent the undesirable CH₄ overoxidation side reactions. For photocatalytic oxidation of methane under ambient temperature, the products yield of 1499.6 μmol g_cat^-1 h^-1 with a primary products selectivity of 77.9% was achieved over Ag-AgBr/ZnO, which demonstrate remarkable improvement compared to Ag/ZnO (1089.9 μmol g_cat^-1 h^-1, 40.1%). The superior activity and selectivity result from the promoted charge separation and the redox potential matching with methane activation after introducing AgBr species. Mechanism investigation elucidated that the photo-generated holes transferred from the valence band of ZnO to that of AgBr, which prevent H₂O oxidation and enhance the selective generation of •OOH radical.

Accelerated charge migration and proton transfer to the reaction site are critical factors for improving photocatalytic efficiency. However, realizing both simultaneously is challenging because of the sluggish water (proton source) oxidation kinetics and interdependent redox reactions. Herein, we design an imide and hydrogen bond to connect carbon nitride ports of the D-π-A system with the dual-engineered linkages. The system uses an acetylene functional group and an imidazole ring as spatially separated water oxidation and oxygen reduction reaction (ORR) catalytic centers for photogenerated charge separation, respectively. The imine bond is a bridge grafted to the oxidation site to act as a hydrogen proton trap, and the hydrogen bond formed between reduction site and carbon nitride is used as the channel for instantaneous proton delivery to the reduction center. In situ characterization confirms that the linking sites protonation optimizes the pathway of ORR to H₂O₂ and facilitates the *OOH intermediates generated. It is concluded that proton transport plays a critical role in optimizing photocatalytic H₂O₂ production. Our work provides a strategy to improve dynamic proton transfer mechanisms.

Design and preparation of highly efficient zeolite catalysts for gas-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam are attractive but still challenging. Herein, we show a one-pot synthesis of silicalite-1 zeolite nanosheets with rich H-bonded silanols. The key to this success is the use of urea in the synthetic system. Catalytic tests of cyclohexanone oxime gas-phase Beckmann rearrangement show that the silicalite-1 zeolite nanosheets with H-bonded silanols exhibit higher selectivity for caprolactam and longer reaction lifetime than those of the conventional silicalite-1 zeolite. Theoretical simulations reveal that the ammonium decomposed by urea is a critical additive for the formation of H-bond silanols. Obviously, one-pot synthesis of silicalite-1 zeolite nanosheets with rich H-bonded silanols plus excellent catalytic performance in the Beckmann rearrangement offer a new opportunity for development of highly efficient zeolites for catalytic applications in the future.

Selective hydrodeoxygenation of lignin derivatives into aromatic compounds is a promising route for the upgrading of lignin feedstocks. Metal carbide catalysts have exhibited excellent selectivity in hydrodeoxygenation reactions, while their structure-activity relationship is still in ambiguity. Herein, a liquid-phase atomic layer deposition method was employed to synthesize W₂C/SiO₂ catalysts with uniform and size-controllable W₂C nanoparticles. For gas-phase hydrodeoxygenation of lignin-derived m-cresol at 350 °C, these W₂C/SiO₂ catalysts showed superior toluene selectivities (>95%) regardless of the W₂C particle size. An optimal W₂C particle size of ~7 nm was obtained for achieving the highest W₂C-based hydrodeoxygenation rate. In contrast, the turnover rate per surface W site increased almost monotonously as the W₂C particle size increased within 0.7‒15 nm, attributable to high-index planes appeared on the larger W₂C nanoparticles. Kinetic effects of m-cresol and H₂, taken together with temperature-programmed desorption of probe molecules and theoretical treatments, further indicate that the W₂C surface is nearly saturated by adsorbed m-cresol or its derivates under the reaction condition and the H-addition of the C₇H₇* intermediate to form toluene, instead of the initial C-O cleavage in m-cresol, acts as the rate-determining step. A side-by-side comparison between W₂C(102) and W₂C(001) catalyst surfaces in theoretical simulations of m-cresol hydrodeoxygenation verifies that high-index planes can stabilize kinetically-relevant transition states more effectively than the low-index ones, as a result of more available less-coordinated active sites on the former. The above findings bring new mechanistic insights into the site requirements of supported W₂C nanocatalysts, distinct from those metal-catalyzed hydrodeoxygenation of oxygenates.

Both biomass valorization and waste upcycling are important routes to sustain the circular bioeconomy. In this work, we present a chemoenzymatic cascade for selective synthesis of chiral N-arylated aspartic acids from biomass-derived furfural and waste nitrophenols (NPs) by merging robust photo- and electrocatalysis with stereoselective biocatalysis. Concurrent photoelectrocatalytic oxidation of furfural into maleic acid (MA) and fumaric acid (FA) was significantly enhanced by combining catalyst and reaction engineering strategies including identification of a powerful photocatalyst meso-tetra(4-carboxyphenyl)porphyrin, continuous flow technique, enhancing dissolved O₂ and paired electrosynthesis. The overall space-time yield (STY) approached 2.8 g L^-1 h^-1 in a fed-batch process, with the product titer of 28.3 g L^-1. Besides, photoelectrosynthesis of MA/FA was effectively fueled by sunlight, with the STY of up to 3.6 g L^-1 h^-1. Both MA selectivity and yield could be facilely improved to around 89% by reducing the buffer concentrations. Paired electrosynthesis strategy not only resulted in greatly improved MA production at the anode, but also enabled NPs upcycling into value-added aminophenols (APs) at the cathode. The products formed in the two electrode chambers were converted into N-arylated (S)-aspartic acids by a bienzymatic cascade. This work presents a multicatalytic approach for integrating selective biomass valorization and waste upcycling towards sustainable manufacture.

Effective CO₂ adsorption and fast electron injection are two crucial processes of photocatalysts for achieving high-efficiency CO₂ photo-reduction. However, simultaneously enhancing these processes within a single photocatalyst remains a challenging task. Herein, we propose an intriguing edge effect based on the intrinsic atomic structure of g-C₃N₄ nanosheets (NSs) to enhance their CO₂ adsorption and facilitate the transfer of photo-generated electrons to the adsorbed CO₂. By cutting large pieces of g-C₃N₄ NSs into smaller fragments, the exposure of amino groups at the edges of its repeating tri-s-triazine units can be significantly increased. These edge-exposed amino groups serve as active sites for enhancing the CO₂ capture capacity of g-C₃N₄ NSs. As we decrease the lateral size of g-C₃N₄ NSs from tens of micrometers to hundreds of nanometers, their CO₂ adsorption capacity increases from 4.74 to 8.56 cm³ g^-1. Reducing the size of g-C₃N₄ NSs also facilitates the transfer of photo-generated electrons to the edge-adsorbed CO₂. Thus, our optimized g-C₃N₄ NSs with the edge effect exhibits a 37-fold enhancement in activity for CO₂ photo-reduction compared to normal g-C₃N₄ NSs under simulated sunlight irradiation. Notably, by introducing Pt cocatalysts, we can control product selectivity from 85.9% CO to 97.9% CH₄.

Designing highly efficient photocatalyst for the valorization of CO₂ is an ideal strategy to reduce greenhouse gas emissions and utilize solar energy. In this study, a S-scheme heterojunction photocatalyst is fabricated by solvothermal impregnation of ZnO on W₁₈O₄₉ for photocatalytic CO₂ N-formylation of aniline. The localized surface plasmon resonance effect of W₁₈O₄₉ improves the absorption capacity for long-wave light significantly, and the hot electrons generated in W₁₈O₄₉ with a high energy can migrate to the conduction band of ZnO and thus enhance the photocatalytic reduction ability. Meanwhile, the S-scheme heterojunction facilitates the separation of photoinduced charge carriers and preserves the redox ability of W₁₈O₄₉/ZnO composite photocatalyst. The conversion of aniline reaches 99.1% after 5 h reaction under visible light irradiation at room temperature with an N-formylaniline selectivity of 100%. A possible photocatalytic reaction mechanism is proposed. This study paves a promising way for the design of highly efficient photocatalyst and the sustainable utilization of CO₂.

The location of aluminum within the framework or extra-framework of zeolites is a critical factor in determining its catalytic performance. Despite extensive research on the identification and formation mechanism of extra-framework aluminum (EFAl), its impact on catalytic performance requires further investigation. Herein, mordenite (MOR) zeolites with comparable acid density within the 8MR and 12MR channels but different EFAl contents were prepared, and their catalytic roles were examined in syngas conversion. Intelligent gravimetric analysis, model experiment of ethylene conversion and thermogravimetric analysis demonstrate that the existence of EFAl species can inhibit the secondary conversion of ethylene to long chain hydrocarbons (i.e., C₅₊) as well as the over-accumulation of carbonaceous species. However, excessive EFAl species lead to rapid deactivation due to restricted space and thus severe diffusion limitation. MOR zeolite with a moderate amount of EFAl species achieves a superior ethylene selectivity and exhibits an enhanced stability in syngas conversion when combined with ZnAlO_x oxide. The insights gained in this work provide important guidance for the design of more efficient zeolite-based catalysts.

Clean catalytic oxidation has a broad prospect in the modern chemical engineering and energy chemistry fields. However, unexpected over-oxidation and disruptive degradation are frequently induced by excessive reactive oxygen species (ROS). Herein, we reported a new ROS-free approach to effectively drive O₂ to be activated into highly reactive surface peroxo species through enzyme-mimicking mechanism. Benefiting from the dual-metal synergy effect between Cu and Co active sites, ROS (H₂O₂ and OH^•) is generated in situ while further scavenged completely into surface peroxo species, which gives rise to very high selectivity and extremely high carbon balance. For example, the CuCo/N-C catalyst affords >99.8% conversion and 94.5% selectivity to 2,5-furanedicarboxylic acid at 25 °C for 6 h in the aerobic oxidation of biomass platform 5-hydroxymethylfurfural. Moreover, it achieved exceptional performance in the oxidation of a variety of hydroxyl compounds to organic acids with high yields (89.9%-99.5%) at a mild temperature (25-40 °C). This exploration introduces an innovative clue for emulating enzyme catalysts, thereby enriching our comprehension and advancement of biologically inspired catalytic oxidations.

In this study, we unveil a conceptual technology for fabricating artificial metalloenzymes (ArMs) by deeply integrating hemin into protein scaffolds via a protein refolding process, a method that transcends the conventional scope of surface-level modifications. Our approach involves denaturing proteins, such as benzaldehyde lyase, green fluorescent protein, and Candida antarctica lipase B, to expose extensive reactive amino acid residues, which are then intricately linked with hemin using orthogonal click reactions, followed by protein refolding. This process not only retains the proteins’ structural integrity but expands proteins’ functionality. The most notable outcome of this methodology is the hemin@BAL variant, which demonstrated a remarkable 83.7% conversion rate in cyclopropanation reactions, far surpassing the capabilities of traditional hemin-based catalysis in water. This success highlights the significant role of protein structure in the ArMs’ activity and marks a substantial leap forward in chemical modification of proteins. Our findings suggest vast potentials of protein refolding approaches for ArMs across various catalytic applications, paving the way for future advancements in synthetic biology and synthetic chemistry.

High-energy-density (HED) fuels (e.g. JP-10) are of great importance in safeguarding territorial air security, since they can increase the flight range and payload of military aircrafts. To reduce the reliance on limited petroleum source, the production of HED fuel with renewable biomass feedstocks is highly appealing. But currently, most of the synthetic biofuels, due to their intrinsic ring structure, are incapable of competing with JP-10 in terms of energy density and freezing point. By emulating the structural characteristic of JP-10, we herein design and prepare a special C₁₆ fused tetracyclic biofuel using renewable cyclopentanone and benzoquinone as feedstocks. Key to success depends on selective dehydration of vicinal diol (dimer of cyclopentanone) over Amberlyst-15 in [Hmim]Cl. The Amberlyst-15/[Hmim]Cl system effectively suppresses the dominant pinacol-type rearrangement pathway and also exhibits good reusability for the dehydration. The hydrogen-bonding interaction between vicinal diol and imidazolium ring, as well as electrostatic force between carbocation intermediate and chloride anion contribute to the high diene selectivity. The compact ring framework gives rise to a density of 0.966 g/mL, combustion heat of 43.1 MJ/L, freezing point of ‒67 °C, and kinematic viscosity of 12.4 cSt, which are comparable to the properties of JP-10. It is expected that this as-prepared HED biofuel may potentially serve as a renewable alternative to petroleum fuel JP-10.

The combination of photoelectrochemical water oxidation hydrogen peroxide (H₂O₂) on the anode and hydrogen evolution on the cathode increase the value of the water splitting process. However, the sluggish water oxidation kinetics and slow carrier transport limit the generation of H₂O₂. In this study, to promote H₂O₂ production, the surface of a Mo doped BiVO₄ photoanode was modified with CoO_x co-catalyst. The resulting CoO_x/Mo-BiVO₄ photoanode generates H₂O₂ at a rate of 0.39 μmol min^-1 cm^-2 with a selectivity of 76.9% at 1.7 V_RHE. The experimental results indicate that CoO_x decorated on Mo-BiVO₄ kinetically favors the H₂O₂ production via reduced band bending, while inhibiting H₂O₂ decomposition. According to density functional theory calculations, the loading of CoO_x enhances the efficiency of the Mo-BiVO₄ photoanode in generating H₂O₂. Moreover, the in-situ generated H₂O₂ through CoO_x/Mo-BiVO₄ was applied to the degradation of tetracycline in aqueous solution, finding that CoO_x/Mo-BiVO₄ exhibits the best performance among the catalysts evaluated. This work demonstrates that the CoO_x co-catalyst can effectively facilitate the water oxidation to H₂O₂, opening a way for its application in situ water remediation.

Constructing well-defined interfaces in catalysts is a highly effective method to accelerate reactions with multiple intermediates. In this study, we developed a heterostructure catalyst combining fcc NiCu and hcp Ni₃N, aiming at achieving superior performance in alkaline hydrogen electrocatalysis. The NiCu/Ni₃N not only overcomes the inadequate hydroxyl binding energy performance of NiCu alloys but also solves the problems of insufficient active sites found in most Ni/Ni₃N. Experimental results and density functional theoretical calculations reveal that the formation of heterostructure significantly depends on the amount of Cu. This approach effectively prevents the side effects of increased catalyst particle size, typically resulting from the high temperatures and prolonged reaction times required for conventional synthesis of Ni/Ni₃N. The interface of this heterostructure induces a distinctive overlapping effect that enhances the adsorption of water and lowers the energy barrier for the rate-determining step. The NiCu/Ni₃N catalyst shows an impressive activity of 71.8 mA mg^-1 at an overpotential of 50 mV, a 14.7 times efficiency enhancement compared to pure Ni and comparable to that of low-loaded commercial Pt/C. This research highlights the potential of NiCu/Ni₃N in advancing catalyst development.

Electrocatalytic nitrogen reduction reaction under ambient conditions is a promising pathway for ammonia synthesis. Currently nitrogen reduction reactions are carried out in N₂-saturated environments and use high-purity nitrogen as feedstock, which is costly. Here, we prepared carbon-coated ultra-low 4d metal Ru-doped liquid metal Ga (Ru_0.06/LM@C) for NRR over a wide range of N₂ concentrations. Comprehensive analyses show that the introduction of the ultra-low 4d element Ru can effectively adjust the electronic structure through orbital interactions, thus enhancing the adsorption of nitrogen-containing intermediates. The liquid catalyst utilized its mobility to provide a higher density of active sites. In addition, the material Ru_0.06/Ga@C itself has the ability to promote product desorption. The three act synergistically to optimize the N₂ mass transfer path, thereby increasing the *NNH coverage and further improving the ammonia yield over a wide range of N₂ concentrations. The maximum NH₃ yield of the catalyst can reach 126.0 μg h^-1 mg_cat^-1 (at -0.3 V vs. RHE) with high purity N₂ as feed gas, and the Faraday efficiency is 60.4% at -0.1 V vs. RHE. Over a wide range of N₂ concentrations, the NH₃ yield of the catalyst was greater than 100 μg h^-1 mg_cat^-1 with a Faraday efficiency higher than 47%. The catalytic performance is much higher than that of solid Ga@C and reported p-block metal-based catalysts.