Direct formic acid fuel cells (DFAFCs) have attracted considerable attention due to their high energy density and environmental benefits; however, their commercial application is hindered by the low activity, poor stability, and CO poisoning susceptibility of conventional Pd-based anode catalysts. In this study, we develop a facile and green aqueous synthesis strategy for fabricating ultrafine alpha-phase palladium hydride nanoparticles supported on carbon (alpha-PdH/C) through a combination of sonochemical and wet chemical reduction methods. The as-prepared alpha-PdH/C catalyst exhibits a uniform particle size of 3.62 +/- 0.17 nm and a high electrochemical surface area of 131.28 m2 g-1. It achieves a superior mass activity of 3.68 A mg-1 for the formic acid oxidation reaction (FAOR), which is 3.35 times higher than that of Pd/C, along with significantly enhanced durability, showing negligible activity decay after 1000 cycles. In situ spectroscopic studies reveal that the FAOR reaction follows the formate pathways with negligible CO generation, a behavior attributed to the tensile strain induced by interstitial hydrogen atoms. This work provides an efficient Pd-based catalyst with remarkable performance and offers new insights into the design of advanced anodic electrocatalysts for DFAFCs.

We report a general acridine/thiol cooperative photocatalytic system for the metal- and base-free decarboxylative hydrogenation of carboxylic acids under mild conditions. This method accommodates a broad range of substrates with high chemoselectivity and excellent functional group tolerance. Moreover, the system operates efficiently in both batch and continuous flow modes, providing a practical and scalable protocol.

Molecular catalysts for the electrocatalytic ammonia oxidation reaction (eAOR) have much to offer in terms of mechanistic investigations and practical energy issues. This work reports the use of complex [Ru(pdc-κ-N1O2)(bpy)(NH3)] (Ru-NH 3 ) (H2pdc = 2, 6-pyridinedicarboxylic acid; bpy = 2,2'-bipyridine) bearing a readily accessible pdc2- ligand to catalyze ammonia oxidation under electrochemical conditions. The rich structural variations of Ru-NH 3 in coordinating solvents and an ammonia atmosphere were fully characterized by cyclic voltammograms (CVs), NMR, and XRD. CV experiments showed that Ru-NH 3 promotes electrocatalytic ammonia oxidation at a low overpotential of 0.85 V with a calculated catalytic rate (k obs) of 18.9 s-1. Controlled potential electrolysis (CPE) at an applied potential of 0.3 V vs Fc+/0 achieves 76.1 equiv of N2 with a faradaic efficiency of 89.8%. Experimental and computational analyses indicated that oxidation of Ru-NH 3 generates a reactive Ru III -NH 3 intermediate, which undergoes sequential electron and proton transfer steps to form a Ru VI ≡N species. N-N bond formation occurs via the nucleophilic attack of an ammonia molecule on the Ru VI ≡N moiety with a facile barrier of 8.6 kcal/mol. Eventually, N2 evolved as the product after releasing two electrons and three protons.

The versatile architecture of covalent organic frameworks (COFs) provides a powerful platform for tailoring their functions. Herein, we demonstrate the molecular engineering of 2D ionic COF nanosheets (iCONs) to reach a family of organic polymeric catalysts with tunable acidity. These solid acidic iCONs are synthesized through Schiff base condensation of the ionic monomer triaminoguanidinium chloride and the aromatic aldehydes with different surface groups. Compared with that in the monomer, the Cl- in iCON matrix tends to be near the framework H atom, generating a new Bronsted acid site with much short Cl-similar to H+ distance that resembles HCl. As a result, these iCONs are highly active in the typical acid reactions of aldol condensation and dehydration of fructose into 5-hydroxymethylfurfural (HMF). The shorter Cl- similar to H+ distance, the better acid catalytic activity. The catalyst DHPA-TG(Cl) reaches a high HMF yield of above 97 % within a short reaction time of 15 min, providing the turnover frequency (TOF) as high as 155.2 h(-1). Facile recycling and stable reusability are also observed. The free energy profiles of these iCONs catalyzing fructose conversion to HMF confirm the function of Cl-similar to H+ units in lowering the energy barrier of the rate-determining step for the water release in the HMF synthesis.

An efficient and regioselective intramolecular tetradehydro-Diels-Alder (TDDA) reaction of enediynols has been realized under mild conditions. This strategy provided a general, concise, and atom-economical approach to synthesize a diverse array of functionalized fluorenols. In addition, the corresponding fluorenol products are readily converted to highly substituted phenanthrene and benzo[b]fluorene derivatives. Control experiments revealed that the newly developed CuI/ortho-phenylenediamine catalytic system greatly enhanced the reactivity of this transformation.

In the context of rising CO2 emissions driven by global dependence on fossil fuels, carbon capture and utilization (CCU)has emerged as a key solution for mitigating climate change by converting CO2 into high valuable industrial products. Conventional Metal-organic frameworks(MOFs)show great promise in the CCU field due to their unique structural and physicochemical properties. This review provides a novel perspective on the trans-formative role of MOFs and their derivatives in advancing CCU technologies. It systematically analyzes the design strategies for pristine MOFs-including structural tuning, metal node engineering, chemical functionalization, and composite formation-as well as the property regulation of MOF-derived porous carbons and metal oxides. Their applications are discussed in both CO2 capture(via adsorption and chemical absorption)and catalytic conversion(via photocatalysis and electrocatalysis). In the context of carbon neutrality goals, this study underscores the promising potential of MOFs to facilitate the industrialization of diverse CCU technologies, while also acknowledging the persisting challenges. Focused research addressing these barriers is crucial to accelerating the real deployment of MOF-enabled CCU systems.

Solar-to-heat conversion represents a promising approach for wide spread sustainable energy applications. The strategic manipulation of defect states in wide-bandgap semiconductors holds transformative potential for solar energy harvesting and yet has not been systematically studied. Herein, we present a transition metal nitride units hybridization strategy in the TiO2 matrix (MN-TiO2) to adjust the electronic structure, thereby extending its solar absorption from similar to 400 nm up to 2500 nm. The optimized CrN-TiO2 exhibits photothermal internal efficiencies as high as 98.0 +/- 1.6%, surpassing mono-doped counterparts by 21.2%. This enhanced performance is attributed to the unique Cr and N units derived in TiO2 by co-doping, which generates a delocalized intermediate band via the interaction between dopant atoms with TiO2 host lattice. The high photothermal performance of Cr, N co-doped TiO2 (CrN-TiO2) enables a remarkable solar steam generation rate of 2.07 kg m(-2) h(-1) and over 94% efficiency under one sun irradiation, surpassing most current results of 2D evaporator (1.64 kg m(-2) h(-1)). When fabricated onto a melamine sponge, our CrN-TiO2-H 3D evaporator can reach up to ultra-high evaporation rate of 4.59 kg m(-2) h(-1), which has great potential for seawater desalination and waste water purification.

Due to high thermodynamic stability, the direct generation of formic acid by CO2 hydrogenation is not easy to achieve experimentally. However, when Nakahara and coworkers studied the equilibrium of formic acid reversibly decomposing into CO2 and H2, they found that using imidazolium formate ionic liquid as an additive could shift the reaction equilibrium to the formic acid side. Subsequently, imidazolium acetate ionic liquid and imidazolium bicarbonate ionic liquid have also been experimentally proven to be able to be used for CO2 hydrogenation to directly produce formic acid. In order to investigate the mechanism of action of ionic liquids in the process of CO2 catalyzed hydrogenation to formic acid, we performed DFT calculations. The results showed that, after the hydrogenation of CO2 to formic acid, the ionic liquids and formic acid molecules form adducts through hydrogen bonding, and then stabilize the product formic acid. The further use of methyl to replace H at the position of the cation R3 of the ionic liquids can improve the ability of the ionic liquids to stabilize formic acid, which also supports the experimental work of Nakahara and coworkers. In addition, among the three ionic liquids, the imidazolium acetate ionic liquid had the best stabilizing effect on formic acid, and the second best is the imidazolium formate ionic liquid, while the imidazolium bicarbonate ionic liquid has a relatively weak stabilizing ability.

Conversion of solar spectrum to heat has attracted widespread attentions. However, the efficient transformation of light in the ultraviolet region to heat is a great challenge. UV light-responsive TiO2 is herein studied for the photothermal conversion process. We found that N-doped TiO2 can show an increased photothermal internal conversion efficiency from 65% for TiO2 to 82% for N-TiO2 in the UV range. Hall tests (N T, trap density) and DFT simulations (E T, trap position) revealed that the defect density of deep-level defect states is greatly increased upon N doping. Accordingly, it is deduced that the photo-to-thermal process occurs through a defect-related nonradiative transition, and its efficiency (eta) is strongly correlated with the defect states density (N T) and defect energy states (E T). Furthermore, this understanding of defect-correlated photothermal conversion could extend to other nonmetallic dopant systems (i.e., S dopants and the O vacancy).

The first catalytic enantioselective [5+1] cycloaddition reactions of C,N-cyclic azomethine imines with isocyanides are reported herein. The method displays a broad substrate scope and atom-economy. A series of chiral tetrahydroisoquinoline containing indole skeletons were obtained in up to 90% yield with 95% ee under mild reaction conditions. A possible catalytic model was also proposed.

Activated carbon with abundant nanoporous structures can effectively adsorb 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) molecules. However, an atomistic understanding of its underlying adsorption mechanism is still urgently needed because TCDD, given its strong toxicity, requires strict testing conditions in experiments. In this work, a series of grand canonical Monte Carlo (GCMC) simulations were performed to evaluate the effects of the slit width and pore size distribution (PSD) of activated carbons on TCDD adsorption. The microstructural analyses of TCDD within nanoslits demonstrate that when the slit width exceeds 0.8 nm, the orientation of TCDD molecules inclines about 30 degrees along the axis's normal direction, causing the adsorption amount to increase rapidly. When the slit width exceeds 2.0 nm, its disordered orientation causes the adsorption amount to reach a maximum value. Based on this understanding, we determined the effective specific pore volume (or effective specific surface area) for TCDD adsorption. In combination with the full width at half-maximum (FWHM) of the PSD, we propose the experimentally measurable structural parameter V-H>0.8/FWHM (or S-H>0.8/FWHM) and use it as an indicator to reflect the TCDD adsorption performance of different activated carbons. A high structural parameter of activated carbon can indicate a high TCDD adsorption amount.

In 2022, Beller and coworkers achieved the reversible hydrogenation of CO2 to formic acid using a Mn(I)–PN5P complex with excellent activity and reusability of the catalyst. To understand the detailed mechanism for the reversible hydrogen release–storage process, especially the effects of the transition metal center in this process, we employed DFT calculations according to which Ru(II) and Fe(II) are considered as two alternatives to the Mn(I) center. Our computational results showed that the production of formic acid from CO2 hydrogenation is not thermodynamically favorable. The reversible hydrogen release–storage process actually occurs between CO2/H2 and formate rather than formic acid. Moreover, Mn(I) might not be a unique active metal for the reversible hydrogenation of CO2 to formate; Ru(II) would be a better option.

Comprehensive Summary In this study, a novel approach is proposed to achieve the uniformly dispersed Ru nanoparticles with N coordination loaded on three‐dimensionally ordered macro/mesoporous carbon (3DOMMC) through simultaneous pyrolysis of Ru 3+ and cyanamide on 3DOMMC. In an alkaline medium, the synthesized catalysts exhibit exceptional hydrogen evolution reaction (HER) performance. Specifically, Ru‐N/3DOMMC demonstrates a significantly low overpotential of 13.8 mV to achieve a current density of 10 mA·cm –2 , and it exhibits a mass activity 17.5 times higher than that of commercial Pt/C. The outstanding performance could be attributed to the ultrahigh Ru dispersion and more efficient contact between active sites and reactant, which derived from the large specific surface area and interconnective three‐dimensionally macro/mesopores of 3DOMMC.

Three cheap DESs comprising of N-methyldiethanolamine (MDEA) and imidazole (Im), 1,2,4-triazole, and tetrazole were investigated for capturing SO2 at low concentrations. Surprisingly, with the addition of Im, the SO2 absorption capacity and desorption efficiency were improved. Spectroscopic analysis and quantum chemical calculations confirmed that MDEA-Im effectively and reversibly captured SO2 through the hydrogen bond network and synergistic action between MDEA and Im.

The co-conversion of CH4 and CO2 has emerged as a challenging issue in C1 chemistry. Converting these gases into a high-value product like acetic acid is an attractive solution. In this study, we employed density-functional theory calculations to design dual-active single-atom catalysts M/In2O3 (M=Co, Ni, Cu, Zn, Rh, Pd, Ag, Cd), which incorporated oxygen vacancies. These catalysts were created by introducing metal M into the surface of In2O3 (111) through doping. Cu/In(2)O3, Zn/In2O3, Ag/In2O3, and Cd/In(2)O3 were selected based on the stability of forming single-atom catalysts. Our findings indicated that the formation of the M/In2O3 surface activates the In surface activity and significantly lowers the activation energy for methane dehydrogenation. Among them, the Cu-1-O-3 species on the Cu/In2O3 surface demonstrates a lower activation energy for methane dehydrogenation and C-C coupling reactions. The "H-O-C-O" hydrogenation of CH3COO* species bonded with the "n"-type structure is more realistic. Microkinetic analysis indicated that the average turnover frequency for the forming of acetic acid on the Cu/In2O3 surface is three orders of magnitude greater than that of methyl formate. This research provides theoretical support for the development of copper single-atom catalysts for the efficient conversion of CO2 and CH4 into acetic acid.

The development of novel absorbents is essential for SO2 removal. In this study, a novel ionic liquid (IL, [BHEP][HSO4]) was prepared, and water was selected as the co-solvent. The density and viscosity of aqueous [BHEP][HSO4] were measured and the SO2 absorption performance was systematically investigated. Furthermore, the thermodynamic properties of SO2 in aqueous [BHEP][HSO4] were calculated. Additionally, the mechanism of SO2 absorption in aqueous [BHEP][HSO4] was confirmed using Fourier-transform infrared and nuclear magnetic resonance spectroscopy. It showed that [BHEP][HSO4] absorbed 0.302 g.g(-1) (g SO2/g IL) at an SO2 partial pressure of 2000 mu l. L-1 at 303.2 K, and the SO2 desorption enthalpy was -39.63 kJ.mol(-1). The mechanistic study confirmed the chemical absorption of SO2 in aqueous [BHEP][HSO4]. (C) 2022 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Despite the great progress of flexible perovskite solar cells (f-PSCs), it still faces several challenges during the homogeneous fabrication of high-quality perovskite thin films, and overcoming the insufficient exciton dissociation. To the ends, we rationally design the ferroelectric two-dimensional (2D) perovskite based on pyridine heterocyclic ring as the organic interlayer. We uncover that incorporation of the ferroelectric 2D material into 3D perovskite induces an increased built-in electric field (BEF), which enhances the exciton dissociation efficiency in the device. Moreover, the 2D seeds could assist the 3D crystallization by forming more homogeneous and highly-oriented perovskite crystals. As a result, an impressive power conversion efficiency (PCE) over 23 % has been achieved by the f-PSCs with outstanding ambient stability. Moreover, the piezo/ferroelectric 2D perovskite intrigues a decreased hole transport barriers at the ITO/perovskite interface under tensile stress, which opens new possibilities for developing highly-efficient f-PSCs.

Direct dehydrogenation of propane (PDH) has already been implemented worldwide in industrial processes to produce value-added propylene. The discovery of earth-abundant and environmentally friendly metal with high activity in C-H cleavage is of great importance. Co species encapsulated within zeolite are highly efficient for catalyzing direct dehydrogenation. However, exploring a promising Co catalyst remains a nontrivial target. Direct control of the regioselective distribution of Co species in the zeolite framework through altering their crystal morphology gives opportunities to modify the metallic Lewis acidic features, thus providing an active and appealing catalyst. Herein, we achieved the regioselective localization of highly active subnanometric CoO clusters in straight channels of siliceous MFI zeolite nanosheets with controllable thickness and aspect ratio. The subnanometric CoO species were identified by different types of spectroscopies, probe measurements, and density functional theory calculations, as the coordination site for the electron-donating propane molecules. The catalyst showed promising catalytic activity for the industrially important PDH with propane conversion of 41.8% and propylene selectivity higher than 95% and was durable during 10 successive regeneration cycles. These findings highlight a green and facile method to synthesize metal-containing zeolitic materials with regioselective metal distribution and also to open up a future perspectives for designing advanced catalysts with integrated advantages of the zeolitic matrix and metal structures.

Hydrogen energy is the answer to the global energy crisis in the close future. Hydrogen is generable from various methods including electrolysis, steam methane reforming, thermal decomposition and photocatalyzed generation from all sources. Mo2C-related catalysts are highly active in hydrogen generation from formic acid at elevated temperatures. In this work, Mo2C and Co-doped Mo2C nanoparticles present high activity in hydrogen generation from formic acid under ultraviolent light at room temperature without any additive. The addition of Mo2C and Co-doped Mo2C nanoparticles in photocatalyzed formic acid decomposition improves the H2 productivity and selectivity greatly and reduces non-H2 productive formic acid consumption under ultraviolet light. A H2 production of 2890 μmol·g−1·h−1 yielded on 5-CoMo2C. The H2 selectivity of the catalyzed formic acid decomposition is 5 times that of the non-catalyzed reaction under the same condition. The complete formation of Mo2C phase is key to the high photocatalytic activity, owning to both prolonged calcination time and Co doping. With Co doping, the Mo2C phase formation was completed within a much shorter calcination time, and the obtained catalysts present higher H2 productivity compared to non-doped catalysts. The use of Mo2C in photocatalyzed H2 production provides a new low-cost H2 production method and in line with pollution control and resourceful utilization of formic acid, which fits the prospect of safe, clean and additive-free H2 generation approach.

This paper investigates the effects of substituents in PNP-type ruthenium complexes in the catalytic hydrogenation of CO2 to formate using the DFT method. Six groups were considered as substituents linked to the P atom of the PNP ligand: hydrogen, methyl, iso-propyl, tert-butyl, cyclopentyl, and cyclohexyl. The substituent effects were analyzed from the perspectives of steric hindrance and promotion of hydrogen bonding. With the joint functions of steric hindrance and hydrogen bonding promotion during the CO2 coordination step, hydride addition step, and HCOO− rotation step, these groups exhibited very different substituent effects. The results showed that the methyl group was the most favorable substituent when the solvent’s effects were not included, as it formed hydrogen bonding with relatively weak steric hindrance. The second favorable substituent was the iso-propyl group, while the tert-butyl group was the most unfavorable one, due to remarkable steric hindrance. When the substituent was cyclopentyl or cyclohexyl, the complex provided a wider open space for the reaction compared with the tert-butyl-substituted complex, because cyclopentyl and cyclohexyl are cyclic groups. Therefore, the principle for choosing the substituent in PNP-type complexes allowing the design of highly efficient catalysts for CO2 hydrogenation indicates that more hydrogen atoms but wider open space are ideal. In addition, the substituent’s effects can be markedly impacted by the solvent used.