Tweaking Photo CO2 Reduction by Altering Lewis Acidic Sites in Metalated-Porous Organic Polymer for Adjustable H2/CO Ratio in Syngas Production

Herein, we have specifically designed two metalated porous organic polymers ( Zn-POP and Co-POP ) for syngas (CO+H₂) production from gaseous CO₂. The variable H₂/CO ratio of syngas with the highest efficiency was produced in water medium (without an organic hole scavenger and photosensitizer) by utilizing the basic principle of Lewis acid/base chemistry. Also, we observed the formation of entirely different major products during photocatalytic CO₂ reduction and water splitting with the help of the two catalysts, where CO (145.65 μmol g⁻¹ h⁻¹) and H₂ (434.7 μmol g⁻¹ h⁻¹) production were preferentially obtained over Co-POP & Zn-POP , respectively. The higher electron density/better Lewis basic nature of Co-POP was investigated further using XPS, XANES, and NH₃-TPD studies, which considerably improve CO₂ activation capacity. Moreover, the structure–activity relationship was confirmed via in situ DRIFTS and DFT studies, which demonstrated the formation of COOH* intermediate along with the thermodynamic feasibility of CO₂ reduction over Co-POP while water splitting occurred preferentially over Zn-POP .     

POM-Incorporated CoO Nanowires for Enhanced Photocatalytic Syngas Production from CO2

Utilizing sustainable energy for chemical activation of small molecules, such as CO₂, to produce important chemical feedstocks is highly desirable. The simultaneous production of CO/H₂ mixture (syngas) from photoreduction of CO₂ and H₂O is highly promising. However, the relationships between structure, composition, crystallinity, and photocatalytic performance are still indistinct. Here, amorphous ultrathin CoO nanowires and polyoxometalate incorporated nanowires with even lower crystallinity were synthesized. The POM-incorporated ultrathin nanowires exhibit high photocatalytic syngas production activity, reaching H₂ and CO evolution rates of 11555 and 4165 μmol g⁻¹ h⁻¹ respectively. Further experiments indicate that the ultrathin morphology and incorporation of POM both contribute to the superior performance. Multiple characterizations reveal the enhanced charge–hole separation efficiency of the catalyst would facilitate the photocatalysis.     

Photo-thermal Cooperative Carbonylation of Ethanol with CO2 on Cu2O-SrTiCuO3-x

Carbonylation of ethanol with CO₂ as carbonyl source into value-added esters is of considerable significance and interest, while remains of great challenge due to the harsh conditions for activation of inert CO₂ in that the harsh conditions result in undesired activation of α-C−H and even cleavage of C−C bond in ethanol to deteriorate the specific activation of O−H bond. Herein, we propose a photo-thermal cooperative strategy for carbonylation of ethanol with CO₂, in which CO₂ is activated to reactive CO via photo-catalysis with the assistance of *H from thermally-catalyzed dissociation of alcoholic O−H bond. To achieve this proposal, an interfacial site and oxygen vacancy both abundant SrTiCuO_3-x supported Cu₂O (Cu₂O-SrTiCuO_3-x) has been designed. A production of up to 320 μmol g⁻¹ h⁻¹ for ethyl formate with a selectivity of 85.6 % to targeted alcoholic O−H activation has been afforded in photo-thermal assisted gas-solid process under 3.29 W cm⁻¹ of UV/Vis light irradiation (144 °C) and 0.2 MPa CO₂. In the photo-driven activation of CO₂ and following carbonylation, CO₂ activation energy decreases to 12.6 kJ mol⁻¹, and the cleavage of alcoholic α-C−H bond has been suppressed.     

Solar-Driven CO2 Conversion via Optimized Photothermal Catalysis in a Lotus Pod Structure

Photothermal CO₂ reduction is one of the most promising routes to efficiently utilize solar energy for fuel production at high rates. However, this reaction is currently limited by underdeveloped catalysts with low photothermal conversion efficiency, insufficient exposure of active sites, low active material loading, and high material cost. Herein, we report a potassium-modified carbon-supported cobalt (K⁺−Co−C) catalyst mimicking the structure of a lotus pod that addresses these challenges. As a result of the designed lotus-pod structure which features an efficient photothermal C substrate with hierarchical pores, an intimate Co/C interface with covalent bonding, and exposed Co catalytic sites with optimized CO binding strength, the K⁺−Co−C catalyst shows a record-high photothermal CO₂ hydrogenation rate of 758 mmol g_cat⁻¹ h⁻¹ (2871 mmol g_Co⁻¹ h⁻¹) with a 99.8 % selectivity for CO, three orders of magnitude higher than typical photochemical CO₂ reduction reactions. We further demonstrate with this catalyst effective CO₂ conversion under natural sunlight one hour before sunset during the winter season, putting forward an important step towards practical solar fuel production.     

Long-Term Stable Hydrogen Production from Water and Lactic Acid via Visible-Light-Driven Photocatalysis in a Porous Microreactor

Photocatalytic hydrogen (H₂) production is significant to overcome challenges like fossil fuel depletion and carbon dioxide emission, but its efficiency is still far below that which is needed for commercialization. Herein, we achieve long-term stable H₂ bubbling production from water (H₂O) and lactic acid via visible-light-driven photocatalysis in a porous microreactor (PP12); the catalytic system benefits from photocatalyst dispersion, charge separation, mass transfer, and dissociation of O−H bonds associated with H₂O. With the widely used platinum/cadmium-sulfide (Pt/CdS) photocatalyst, PP12 leads to a H₂ bubbling production rate of 602.5 mmol h⁻¹ m⁻², which is 1000 times higher than that in a traditional reactor. Even when amplifying PP12 into a flat-plate reactor with an area as large as 1 m² and extending the reaction time to 100 h, the H₂ bubbling production rate still remains at around 600.0 mmol h⁻¹ m⁻², offering great potential for commercialization.     

Wurtzite CuGaS2 with an In-Situ-Formed CuO Layer Photocatalyzes CO2 Conversion to Ethylene with High Selectivity

We present surface reconstruction-induced C−C coupling whereby CO₂ is converted into ethylene. The wurtzite phase of CuGaS_2. undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO₂ to ethylene (C₂H₄). Upon illumination, the catalyst efficiently converts CO₂ to C₂H₄ with 75.1 % selectivity (92.7 % selectivity in terms of R_electron) and a 20.6 μmol g⁻¹ h⁻¹ evolution rate. Subsequent spectroscopic and microscopic studies supported by theoretical analysis revealed operando-generated Cu²⁺, with the assistance of existing Cu⁺, functioning as an anchor for the generated *CO and thereby facilitating C−C coupling. This study demonstrates strain-induced in situ surface reconstruction leading to heterojunction formation, which finetunes the oxidation state of Cu and modulates the CO₂ reduction reaction pathway to selective formation of ethylene.     

HKUST-1 Derived Hollow C-Cu2−xS Nanotube/g-C3N4 Composites for Visible-Light CO2 Photoreduction with H2O Vapor

As the main component of syngas, reducing CO₂ to CO with high selectivity through photocatalysis could provide a sustainable way to alleviate energy shortage issues. Developing a photocatalytic system with low cost and high performance that is environmentally friendly is the ultimate goal towards CO₂ photoreduction. Herein, an efficient and economic three-component heterojunction photocatalyst is designed and fabricated for converting CO₂ to CO in the absence of organic sacrificial agents. The heterojunction is made of Cu_2−xS nanotubes coated with a carbon layer (C-Cu_2−xS) and g-C₃N₄. By using the classical MOF material HKUST-1 as a precursor, hollow tubular-like metal sulfides (C-Cu_2−xS) with carbon coating were synthesized and further loaded on g-C₃N₄, forming a three-component heterojunction C-Cu_2−xS@g-C₃N₄. The carbon coat in C-Cu_2−xS@g-C₃N₄ acts as an electron reservoir, which facilitates electron–hole pair separation. The optimized C-Cu_2−xS@g-C₃N₄ acted as a photocatalyst in CO₂ reduction with a high reactivity of 1062.6 μmol g⁻¹ and selectivity of 97 %. Compared with bare g-C₃N₄ (158.4 μmol g⁻¹) and C-Cu_2−xS, the reactivity is nearly 7 and 23-fold enhanced and this CO generation rate is higher than most of the reported Cu₂S or g-C₃N₄ composites under similar conditions. The prominent activity may result from enhanced light adsorption and effective charge separation. This work might open up an alternative method for the design and fabrication of high-performance and low-cost photocatalysts for efficiently and durably converting CO₂ to CO with high selectivity.     

Engineering a Copper Single-Atom Electron Bridge to Achieve Efficient Photocatalytic CO2 Conversion

Developing highly efficient and stable photocatalysts for the CO₂ reduction reaction (CO₂RR) remains a great challenge. We designed a Z-Scheme photocatalyst with N−Cu₁−S single-atom electron bridge (denoted as Cu-SAEB), which was used to mediate the CO₂RR. The production of CO and O₂ over Cu-SAEB is as high as 236.0 and 120.1 μmol g⁻¹ h⁻¹ in the absence of sacrificial agents, respectively, outperforming most previously reported photocatalysts. Notably, the as-designed Cu-SAEB is highly stable throughout 30 reaction cycles, totaling 300 h, owing to the strengthened contact interface of Cu-SAEB, and mediated by the N−Cu₁−S atomic structure. Experimental and theoretical calculations indicated that the SAEB greatly promoted the Z-scheme interfacial charge-transport process, thus leading to great enhancement of the photocatalytic CO₂RR of Cu-SAEB. This work represents a promising platform for the development of highly efficient and stable photocatalysts that have potential in CO₂ conversion applications.     

Light-Driven Syngas Production over Defective ZnIn2S4 Nanosheets

Photocatalytic syngas (CO and H₂) production with CO₂ as gas source not only ameliorates greenhouse effect, but also produces valuable chemical feedstocks. However, traditional photocatalytic systems require noble metal or suffers from low yield. Here, we demonstrate that S vacancies ZnIn₂S₄ (V_S-ZnIn₂S₄) nanosheets are an ideal photocatalyst to drive CO₂ reduction into syngas. It is found that building S vacancies can endow ZnIn₂S₄ with stronger photoabsorption, efficient electron–hole separation, and larger CO₂ adsorption, finally promoting both hydrogen evolution reaction (HER) and CO₂ reduction reaction (CO₂RR). The syngas yield of CO and H₂ is therefore significantly increased. In contrast to pristine ZnIn₂S₄, the syngas yield over V_S-ZnIn₂S₄ can be improved by roughly ≈4.73 times and the CO/H₂ ratio is modified from 1:4.18 to 1:1. Total amount of syngas after 12 h photocatalysis is as high as 63.20 mmol g⁻¹ without use of any noble metals, which is even higher than those of traditional noble metal-based catalysts in the reported literatures. This work demonstrates the critical role of S vacancies in mediating catalytic activity and selectivity, and highlights the attractive ability of defective ZnIn₂S₄ for light-driven syngas production.     

Non-Interacting Ni and Fe Dual-Atom Pair Sites in N-Doped Carbon Catalysts for Efficient Concentrating Solar-Driven Photothermal CO2 Reduction

Solar-to-chemical energy conversion under weak solar irradiation is generally difficult to meet the heat demand of CO₂ reduction. Herein, a new concentrated solar-driven photothermal system coupling a dual-metal single-atom catalyst (DSAC) with adjacent Ni−N₄ and Fe−N₄ pair sites is designed for boosting gas-solid CO₂ reduction with H₂O under simulated solar irradiation, even under ambient sunlight. As expected, the (Ni, Fe)−N−C DSAC exhibits a superior photothermal catalytic performance for CO₂ reduction to CO (86.16 μmol g⁻¹ h⁻¹), CH₄ (135.35 μmol g⁻¹ h⁻¹) and CH₃OH (59.81 μmol g⁻¹ h⁻¹), which are equivalent to 1.70-fold, 1.27-fold and 1.23-fold higher than those of the Fe−N−C catalyst, respectively. Based on theoretical simulations, the Fermi level and d-band center of Fe atom is efficiently regulated in non-interacting Ni and Fe dual-atom pair sites with electronic interaction through electron orbital hybridization on (Ni, Fe)−N−C DSAC. Crucially, the distance between adjacent Ni and Fe atoms of the Ni−N−N−Fe configuration means that the additional Ni atom as a new active site contributes to the main *COOH and *HCO₃ dissociation to optimize the corresponding energy barriers in the reaction process, leading to specific dual reaction pathways (COOH and HCO₃ pathways) for solar-driven photothermal CO₂ reduction to initial CO production.     

Rapid Charge Transfer Endowed by Interfacial Ni-O Bonding in S-scheme Heterojunction for Efficient Photocatalytic H2 and Imine Production

Cooperative coupling of H₂ evolution with oxidative organic synthesis is promising in avoiding the use of sacrificial agents and producing hydrogen energy with value-added chemicals simultaneously. Nonetheless, the photocatalytic activity is obstructed by sluggish electron-hole separation and limited redox potentials. Herein, Ni-doped Zn_0.2Cd_0.8S quantum dots are chosen after screening by DFT simulation to couple with TiO₂ microspheres, forming a step-scheme heterojunction. The Ni-doped configuration tunes the highly active S site for augmented H₂ evolution, and the interfacial Ni−O bonds provide fast channels at the atomic level to lower the energy barrier for charge transfer. Also, DFT calculations reveal an enhanced built-in electric field in the heterojunction for superior charge migration and separation. Kinetic analysis by femtosecond transient absorption spectra demonstrates that expedited charge migration with electrons first transfer to Ni²⁺ and then to S sites. Therefore, the designed catalyst delivers drastically elevated H₂ yield (4.55 mmol g⁻¹ h⁻¹) and N-benzylidenebenzylamine production rate (3.35 mmol g⁻¹ h⁻¹). This work provides atomic-scale insights into the coordinated modulation of active sites and built-in electric fields in step-scheme heterojunction for ameliorative photocatalytic performance.     

A 2D cadmium metal–organic framework: Synthesis,structure and luminescence sensing for chromate,permanganate, cupric,silver and ferric

A multi-responsive Cd metal–organic framework {[Cd (ttpe)(H₂O)(ip)]•4H₂O•DMAC}_n ( 1•4H ₂ O•DMAC ) was synthesized using hydrothermal method (ttpe = 1,1,2,2-tetra(4-(1H-1,2,4-triazol-1-yl)phenyl)ethylene, ip = isophthalate, DMAC = N,N-dimethylacetamide), and characterized. 1 exhibits a 2D (4,4) network. The luminescent sensing experimrnts showed that 1•4H ₂ O•DMAC as a new MOF luminescent sensor can detect Cr₂O₇²⁻, CrO₄²⁻, MnO₄⁻, Cu²⁺, Ag⁺ and Fe³⁺ in aqueous solution with simultaneously high efficiency and high sensitivity. The quenching constants K_sv for Cr₂O₇²⁻, CrO₄²⁻, MnO₄⁻, Cu²⁺, Ag⁺ and Fe³⁺ are 4.231 × 10⁴ M⁻¹, 2.471 × 10⁴ M⁻¹, 6.459 × 10³ M⁻¹, 7.617 × 10³ M⁻¹, 1.563 × 10⁴ M⁻¹ and 3.574 × 10⁴ M⁻¹, respectively. The detection limits are 0.094 μM for Cr₂O₇²⁻, 0.108 μM for CrO₄^{2 −} , 0.346 μM for MnO₄⁻, 0.302 μM for Cu²⁺, 0.221 μM for Ag ⁺ , and 0.100 μM for Fe³⁺. 1•4H ₂ O•DMAC exhibits high photocatalytic efficiency for degradation of methylene blue under visible light irradiation.     

A Robust Photocatalytic Hybrid Material Composed of Metal-Organic Cages and TiO2 for Efficient Visible-Light-Driven Hydrogen Evolution

The design of photochemical molecular devices (PMDs) for photocatalytic H₂ production from water is a meaningful but challenging subject currently. Herein, a Pd₂L₄ type metal-organic cage (denoted as MOC-Q2) is designed as a PMD, which consists of two catalytic centers (Pd²⁺) and four photosensitive ligands (L-2) with four pyridine anchoring groups. Subsequently, the MOC-Q2 is combined with TiO₂ to form TiO₂-MOC-Q2 hybrid materials with different MOC-Q2 contents by a facile sol-gel method, which have micro/mesoporous structures and large surface areas. The optimized TiO₂-MOC-Q2 (6.5 wt%) exhibits high H₂ production activity (7.9 mmol g⁻¹ h⁻¹ within 5 h) and excellent durability, giving a TON value of 23477 or 11739 (based on MOC-Q2 or Pd moles) after recycling for 7 rounds. By contrast, the pure MOC-Q2 only shows an ordinary photocatalytic H₂ production rate (0.84 mmol g⁻¹ h⁻¹ within 5 h) in the homogeneous system. It can be deduced that TiO₂ drives the photocatalysis and simultaneously acts as the structure promoter. This study presents a meaningful and distinctive attempt of a new approach for the design and development of MOC-based heterogeneous photocatalysts.     

Bias-Free Solar-Driven Syngas Production: A Fe2O3 Photoanode Featuring Single-Atom Cobalt Integrated with a Silver-Palladium Cathode

Photoelectrochemical syngas production from aqueous CO₂ is a promising technique for carbon capture and utilization. Herein, we demonstrate the efficient and tunable syngas production by integrating a single-atom cobalt-catalyst-decorated α-Fe₂O₃ photoanode with a bimetallic Ag/Pd alloy cathode. A record syngas production activity of 81.9 μmol cm⁻² h⁻¹ (CO/H₂ ratio: ≈1 : 1) was achieved under artificial sunlight (AM 1.5 G) with an excellent durability. Systematic studies reveal that the Co single atoms effectively extract the holes from Fe₂O₃ photoanodes and serve as active sites for promoting oxygen evolution. Simultaneously, the Pd and Ag atoms in bimetallic cathodes selectively adsorb CO₂ and protons for facilitating CO production. Further incorporation with a photovoltaic, to allow solar light (>600 nm) to be utilized, yields a bias-free CO₂ reduction device with solar-to-CO and solar-to-H₂ conversion efficiencies up to 1.33 and 1.36 %, respectively.     

Carbon-Based Electron Buffer Layer on ZnOx−Fe5C2−Fe3O4 Boosts Ethanol Synthesis from CO2 Hydrogenation

The conversion of CO₂ into ethanol with renewable H₂ has attracted tremendous attention due to its integrated functions of carbon elimination and chemical synthesis, but remains challenging. The electronic properties of a catalyst are essential to determine the adsorption strength and configuration of the key intermediates, therefore altering the reaction network for targeted synthesis. Herein, we describe a catalytic system in which a carbon buffer layer is employed to tailor the electronic properties of the ternary ZnO_x−Fe₅C₂−Fe₃O₄, in which the electron-transfer pathway (ZnO_x→Fe species or carbon layer) ensures the appropriate adsorption strength of −CO* on the catalytic interface, facilitating C−C coupling between −CH_x* and −CO* for ethanol synthesis. Benefiting from this unique electron-transfer buffering effect, an extremely high ethanol yield of 366.6 g_EtOH kg_cat⁻¹ h⁻¹ (with CO of 10 vol % co-feeding) is achieved from CO₂ hydrogenation. This work provides a powerful electronic modulation strategy for catalyst design in terms of highly oriented synthesis.     

High Ammonia Uptake of a Metal–Organic Framework Adsorbent in a Wide Pressure Range

Although numerous porous adsorbents have been investigated for NH₃ capture applications, these materials often exhibit insufficient NH₃ uptake, low NH₃ affinity at the ppm level, and poor chemical stability against wet NH₃ conditions. The NH₃ capture properties of M₂(dobpdc) complexes (M=Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, and Zn²⁺; dobpdc⁴⁻=4,4-dioxidobiphenyl-3,3-dicarboxylate) that contain open metal sites is presented. The NH₃ uptake of Mg₂(dobpdc) at 298 K was 23.9 mmol g⁻¹ at 1 bar and 8.25 mmol g⁻¹ at 570 ppm, which are record high capacities at both pressures among existing porous adsorbents. The structural stability of Mg₂(dobpdc) upon exposure to wet NH₃ was superior to that of the other M₂(dobpdc) and the frameworks tested. Overall, these results demonstrate that Mg₂(dobpdc) is a recyclable compound that exhibits significant NH₃ affinity and capacity, making it a promising candidate for real-world NH₃-capture applications.     

Single-Atom Zinc Sites with Synergetic Multiple Coordination Shells for Electrochemical H2O2 Production

Precise manipulation of the coordination environment of single-atom catalysts (SACs), particularly the simultaneous engineering of multiple coordination shells, is crucial to maximize their catalytic performance but remains challenging. Herein, we present a general two-step strategy to fabricate a series of hollow carbon-based SACs featuring asymmetric Zn−N₂O₂ moieties simultaneously modulated with S atoms in higher coordination shells of Zn centers (n≥2; designated as Zn−N₂O₂−S). Systematic analyses demonstrate that the synergetic effects between the N₂O₂ species in the first coordination shell and the S atoms in higher coordination shells lead to robust discrete Zn sites with the optimal electronic structure for selective O₂ reduction to H₂O₂. Remarkably, the Zn−N₂O₂ moiety with S atoms in the second coordination shell possesses a nearly ideal Gibbs free energy for the key OOH* intermediate, which favors the formation and desorption of OOH* on Zn sites for H₂O₂ generation. Consequently, the Zn−N₂O₂−S SAC exhibits impressive electrochemical H₂O₂ production performance with high selectivity of 96 %. Even at a high current density of 80 mA cm⁻² in the flow cell, it shows a high H₂O₂ production rate of 6.924 mol g_cat⁻¹ h⁻¹ with an average Faradaic efficiency of 93.1 %, and excellent durability over 65 h.     

Reversible Switching CuII/CuI Single Sites Catalyze High-rate and Selective CO2 Photoreduction

Herein, we first design a model of reversible redox-switching metal–organic framework single-unit-cell sheets, where the abundant metal single sites benefit for highly selective CO₂ reduction, while the reversible redox-switching metal sites can effectively activate CO₂ molecules. Taking the synthetic Cu-MOF single-unit-cell sheets as an example, synchrotron-radiation quasi in situ X-ray photoelectron spectra unravel the reversible switching Cu^II/Cu^I single sites initially accept photoexcited electrons and then donate them to CO₂ molecules, which favors the rate-liming activation into CO₂^δ−, verified by in situ FTIR spectra and Gibbs free energy calculations. As an outcome, Cu-MOF single-unit-cell sheets achieve near 100 % selectivity for CO₂ photoreduction to CO with a high rate of 860 μmol g⁻¹ h⁻¹ without any sacrifice reagent or photosensitizer, where both the activity and selectivity outperform previously reported photocatalysts evaluated under similar conditions.     

Hybrid Superlattice-Triggered Selective Proton Grotthuss Intercalation in δ-MnO2 for High-Performance Zinc-Ion Battery

A great deal of attention has been paid on layered manganese dioxide (δ−MnO₂) as promising cathode candidate for aqueous zinc-ion battery (ZIB) due to the excellent theoretical capacity, high working voltage and Zn²⁺/H⁺ co-intercalation mechanism. However, caused by the insertion of Zn²⁺, the strong coulomb interaction and sluggish diffusion kinetics have resulted in significant structure deformation, insufficient cycle stability and limited rate capability. And it is still far from satisfactory to accurately modulate H⁺ intercalation for superior electrochemical kinetics. Herein, the terrace-shape δ−MnO₂ hybrid superlattice by polyvinylpyrrolidone (PVP) pre-intercalation (PVP−MnO₂) was proposed with the state-of-the-art ZIBs performance. Local atomic structure characterization and theoretical calculations have been pioneering in confirming the hybrid superlattice-triggered synergy of electron entropy stimulation and selective H⁺ Grotthuss intercalation. Accordingly, PVP−MnO₂ hybrid superlattice exhibits prominent specific capacity (317.2 mAh g⁻¹ at 0.125 A g⁻¹), significant rate performance (106.1 mAh g⁻¹ at 12.5 A g⁻¹), and remarkable cycle stability at high rate (≈100 % capacity retention after 20,000 cycles at 10 A g⁻¹). Therefore, rational design of interlayer configuration paves the pathways to the development of MnO₂ superlattice for advanced Zn−MnO₂ batteries.