Activation Energy Barrier Research Articles

Selective CO2 Reduction to Ethylene Mediated by Adaptive Small‐molecule Engineering of Copper‐based Electrocatalysts

AbstractElectrochemical CO2 reduction reaction (CO2RR) over Cu catalysts exhibits enormous potential for efficiently converting CO2 to ethylene (C2H4). However, achieving high C2H4 selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO2RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu‐based material to a pathway that facilitates CO2 reduction to C2H4 products. An excellent Faraday efficiency (FE) of 63.6 % on C2H4 with a current density of 497.2 mA cm−2 in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH4. The in situ X‐ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cuδ+ during the CO2RR. Furthermore, theoretical calculations demonstrate that the Cuδ+/Cu0 interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C2H4 production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO2 reduction to value‐added chemicals.

Selective CO2‐to‐Syngas Conversion Enabled by Bimetallic Gold/Zinc Sites in Partially Reduced Gold/Zinc Oxide Arrays

AbstractElectrocatalytic CO2‐to‐syngas (gaseous mixture of CO and H2) is a promising way to curb excessive CO2 emission and the greenhouse gas effect. Herein, we present a bimetallic AuZn@ZnO (AuZn/ZnO) catalyst with high efficiency and durability for the electrocatalytic reduction of CO2 and H2O, which enables a high Faradaic efficiency of 66.4 % for CO and 26.5 % for H2 and 3 h stability of CO2‐to‐syngas at −0.9 V vs. the reversible hydrogen electrode (RHE). The CO/H2 ratios show a wide range from 0.25 to 2.50 over a narrow potential window (−0.7 V to −1.1 V vs. RHE). In situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy combined with density functional theory calculations reveals that the bimetallic synergistic effect between Au and Zn sites lowers the activation energy barrier of CO2 molecules and facilitates electronic transfer, further highlighting the potential to control CO/H2 ratios for efficient syngas production using the coexisting Au sites and Zn sites.

Selective CO2 -to-Syngas Conversion Enabled by Bimetallic Gold/Zinc Sites in Partially Reduced Gold/Zinc Oxide Arrays.

Electrocatalytic CO2 -to-syngas (gaseous mixture of CO and H2 ) is a promising way to curb excessive CO2 emission and the greenhouse gas effect. Herein, we present a bimetallic AuZn@ZnO (AuZn/ZnO) catalyst with high efficiency and durability for the electrocatalytic reduction of CO2 and H2 O, which enables a high Faradaic efficiency of 66.4 % for CO and 26.5 % for H2 and 3 h stability of CO2 -to-syngas at -0.9 V vs. the reversible hydrogen electrode (RHE). The CO/H2 ratios show a wide range from 0.25 to 2.50 over a narrow potential window (-0.7 V to -1.1 V vs. RHE). In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy combined with density functional theory calculations reveals that the bimetallic synergistic effect between Au and Zn sites lowers the activation energy barrier of CO2 molecules and facilitates electronic transfer, further highlighting the potential to control CO/H2 ratios for efficient syngas production using the coexisting Au sites and Zn sites.

Sodium-Selenium Batteries with Outstanding Rate Capability by Introducing Cubic Mn2 O3 Electrocatalyst.

With their high volumetric capacity and electronic conductivity, sodium-selenium (Na-Se) batteries have attracted attention for advanced battery systems. However, the irreversible deposition of sodium selenide (Na2 Se) results in rapid capacity degradation and poor Coulombic efficiency. To address these issues, cubic α-Mn2 O3 is introduced herein as an electrocatalyst to effectively catalyze Na2 Se conversion and improve the utilization of active materials. The results show that the addition of 10 wt% Mn2 O3 in the selenium/Ketjen black (Se/KB) composite enhances the conversion from Na2 Se to Se by lowering activation energy barrier and leads to fast sodium-ion kinetics and low internal resistance. Consequently, the Mn2 O3 -based composite delivers a high specific capacity of 635 mAh ⋅ g-1 at 675 mA ⋅ g-1 after 250 cycles as well as excellent cycling stability for 800 cycles with a high specific capacity of 317 mAh ⋅ g-1 even at the high current density of 3375 mA ⋅ g-1 . Due to the cubic Mn2 O3 electrocatalyst, the performance of the composites is superior to existing state-of-the-art Na-Se batteries reported in the literature.

Solvent and Substituent Size Influence on the Cyclochiral Rigidity of Aminomethylene Derivatives of Resorcin[4]arene.

Resorcin[4]arenes (R[4]A) are a group of macrocyclic compounds whose peculiar feature is the presence of eight hydroxyl groups in their structure. The directional formation of intramolecular hydrogen bonds with their participation leads to the formation of a cyclochiral racemic mixture of these compounds. Their stability strongly depends on the substituent and especially the environment in which they are located. The paper discusses the cyclochiral nature of aminomethylene derivatives of R[4]A (AMD-R[4]A). Their cyclochiral rigidity in non-polar solvents has been shown. The influence of the size of the alkyl groups in the amino substituents of AMD-R[4]A on their cyclochiral nature was noted. To calculate the reaction paths for their racemization, the nudged elastic band (NEB) method was employed using the semi-empirical DFT (GFN1-xTB) approach. The calculated activation barrier energies for their racemization in chloroform, obtained through various semi-empirical quantum chemical methods (SE), Hartree-Fock (HF), and density functionals theory (DFT), show good correlation with experimental observations. Among the tested methods, the B38LYP-D4 method is highly recommended due to its fast computational speed and accuracy, which is comparable to the time-consuming double-hybrid DH-revDSD-PBEP86 approach.

Understanding the promotion effect of Pt in the reaction system of water gas shift reaction catalyzed by Pt/α-MoC from theoretical perspectives

Pt/α-MoC is an outstanding catalyst for the low-temperature water gas shift (WGS, CO + H2O → H2 + CO2) reaction, exhibiting elevated activity, stability, and selectivity. In this study, three significant active site models (α-MoC-111, Pt-111, and Pt1/α-MoC-111) in Pt/α-MoC catalyst were established to investigate the promotion effect of Pt on the WGS reaction catalyzed by Pt/α-MoC. The results indicate that a synergistic effect at the metal-carbide interface enhances chemical activity compared to pure Pt-111 and α-MoC-111. Firstly, the surface of Pt1/α-MoC-111 exhibits strong metal-support interaction between Pt single atom and α-MoC-111 surface. Compared to the α-MoC-111 surface, the introduction of Pt strengthens the Mo−Mo bond while weakening the Mo−C bond. Secondly, adding a Pt atom significantly increases adsorption strength for CO and H2O, while decreasing it for products (CO2), oxides (O atom), and by-products (C atom). The advantage of suppressing surface carbon deposition and oxidation is observed on the surface of Pt1/α-MoC-111. Furthermore, elementary reactions from the three mainstream reaction pathways of the WGS reaction are systematically calculated to evaluate catalytic performance among these three active sites. On the Pt1/α-MoC-111 surface, activation energy barriers for H2O dissociation and CO oxidation are reduced. This provides theoretical ideas for designing high-efficiency α-MoC based catalysts in the future.

Hydrogenation of α,β-unsaturated aldehydes over defective UiO-66 with Frustrated Lewis Pairs: Modulation of densities of defect sites via tailoring ligand-vacancies

In this work, defect-rich UiO-66-FA catalysts were synthesized using a modulator-induced defect formation strategy via tailoring ligand-vacancies and applied in the transfer hydrogenation of α,β-unsaturated aldehydes using cyclohexanol as the hydrogen source. The study reveals that the constructed surface defect in UiO-66 promotes the emergence of Zr-OH sites (Lewis base) and the neighboring unsaturated Zr4+ sites (Lewis acid) on the surface of UiO-66-FA, thereby generating solid Frustrated Lewis Pairs (FLPs) sites. Furthermore, the manipulation of the densities of defect sites can establish Zr4+/Zr-OH FLPs sites with improved activity and selectivity to unsaturated alcohols. The findings of this study indicate that the Zr4+/Zr-OH sites possess the ability to activate the CO of aldehydes and -OH of cyclohexanol, resulting in a smaller activation energy barrier and exceptional catalytic performance. Additionally, it is noteworthy that the defective UiO-66 also demonstrates outstanding hydrogenation activity in the direct hydrogenation of α,β-unsaturated aldehydes, with a mere 6.8 Kal/mol activation energy required for the dissociation of H-H bonds. The possible reaction mechanism was proposed based on in situ DRIFT analysis. This work is valuable for the design and preparation of unsaturated aldehydes/ketones hydrogenation catalysts and provides a new idea for the design of solid FLPs catalysts.

A novel sea urchin-shaped copper-incorporated g-C3N4 nanoreactor for high-efficiency selectivity photocatalytic CO2 conversion into CO

Carbon graphene nitride (g-C3N4, CN) is a promising future for photocatalytic CO2 conversion into solar fuels. However, its photocatalytic activity and selectivity are limited to inadequate active sites, low visible light utilization rate, poor CO2 adsorption capacity, and rapid photo-generated carriers recombination rate. Herein, the supramolecular self-assembly method synthesized the sea urchin-like Cu-incorporated g-C3N4 (Cu-CNNTs) nanoreactors. The as-prepared Cu-CNNTs nanoreactor exhibits the photocatalytic reduction of CO2 into CO rate (16.09 μmol g-1h−1), 9.4 times higher than BCN and 3.33 times that of CNHS. The Cu-doping in the six-fold cavity of heptazine units as reaction active centers enrich both the photoelectrons and CO2 molecule. The superior structure of Cu-CNNTs shortens the transmission distance of electrons, accelerating the separation of electron-hole pairs and improving the utilization of light. Theory calculation results demonstrate that the activation energy barrier of the reduction of CO2 to CO is lower than that of CH4. Therefore, Cu-CNNTs exhibit enhanced selectivity and photocatalytic activity for converting CO2 to CO. This result provides valuable insights for the design and synthesis of highly selective and active carbon nitride-based multifunctional photocatalysts.

Atomic Zn-Doping Induced Sabatier Optimum in NiZn0.03 Catalyst for CO2 Electroreduction at Industrial-Level Current Densities.

The Sabatier principle defines the essential criteria for an ideal catalyst in heterogeneous catalysis, while reaching the Sabatier optimum is still challenging in catalyst design. Herein, an elegant strategy is described to reach the Sabatier optimum of Ni electrocatalyst in CO2 reduction reaction (CO2 RR) by atomically Zn doping. The incorporation of 3%Zn single atom into Ni lattice leads to the moderate degrade of d-band center via Ni-Zn electronic coupling, which balances the bonding strengths of *COOH and *CO, resulting in a relative low energy barrier for CO2 activation while not being substantially poisoned by CO. Consequently, NiZn0.03 /C exhibits unique catalytic activity (jCO >100mAcm-2 at -0.6V), wide potential range for selective CO production (FECO >90% from -0.65 to -1.15V), and outstanding long-term stability (FECO >90% during 85h electrolysis at -0.85V). The results provide valuable insights for the rational fabrication of superior non-noble bimetallic electrocatalysts in CO2 electroreduction.

Water Activation Triggered by Cu-Co Double-Atom Catalyst for Silane Oxidation.

High-performance catalysts sufficient to significantly reduce the energy barrier of water activation are crucial in facilitating reactions that are restricted by water dissociation. Herein we present a Cu-Co double-atom catalyst (CuCo-DAC), which possesses a uniform and well-defined CuCoN6 (OH) structure, and works together to promote water activation in silane oxidation. The catalyst achieves superior catalytic performance far exceeding that of single-atom catalysts (SACs). Various functional silanes are converted into silanols with up to 98 % yield and 99 % selectivity. Kinetic studies show that the activation energy of silane oxidation by CuCo-DAC is significantly lower than that of Cu single-atom catalyst (Cu-SAC) and Co single-atom catalyst (Co-SAC). Theoretical calculations demonstrate two different reaction pathways where water splitting is the rate-determining step and it is accelerated by CuCo-DAC, whereas H2 formation is key for its single-atom counterpart.

Water Activation Triggered by Cu−Co Double‐Atom Catalyst for Silane Oxidation

AbstractHigh‐performance catalysts sufficient to significantly reduce the energy barrier of water activation are crucial in facilitating reactions that are restricted by water dissociation. Herein we present a Cu−Co double‐atom catalyst (CuCo‐DAC), which possesses a uniform and well‐defined CuCoN6(OH) structure, and works together to promote water activation in silane oxidation. The catalyst achieves superior catalytic performance far exceeding that of single‐atom catalysts (SACs). Various functional silanes are converted into silanols with up to 98 % yield and 99 % selectivity. Kinetic studies show that the activation energy of silane oxidation by CuCo‐DAC is significantly lower than that of Cu single‐atom catalyst (Cu‐SAC) and Co single‐atom catalyst (Co‐SAC). Theoretical calculations demonstrate two different reaction pathways where water splitting is the rate‐determining step and it is accelerated by CuCo‐DAC, whereas H2 formation is key for its single‐atom counterpart.

Hydrothermal Synthesis of Highly Crystalline Zwitterionic Vinylene-Linked Covalent Organic Frameworks with Exceptional Photocatalytic Properties.

Ionic covalent organic frameworks (COFs) featuring both crystallinity and ionic characteristics have attracted tremendous attention in recent years. Compared with single anion- or cation-containing ionic COFs, zwitterionic COFs possess unique functionalities beyond single ionic COFs such as tunable charge density and superhydrophilic and highly ion-conductive characteristics, endowing them with huge potential in various applications. However, it remains a considerable challenge to directly synthesize robust, highly crystalline zwitterionic COFs from the original building blocks. Herein, we report a green hydrothermal synthesis strategy to prepare highly crystalline zwitterionic vinylene-linked COFs (ZVCOFs) from the predesigned zwitterionic building block by utilizing 4-dimethylaminopyridine (DMAP) as the high-efficiency catalyst for the first time. Detailed theoretical calculations and experiments revealed that both the high catalytic activity of DMAP and the unique role of water contributed to the formation of highly crystalline ZVCOFs. It was found that the participation of water could not only remarkably reduce the activation energy barrier and thus enhance the reaction reversibility but also enable the hydration of zwitterionic sites and facilitate ordered layered arrangement, which are favorable for the ZVCOF crystallization. Benefiting from the highly π-conjugated structure and hydrophilic characteristic, the obtained ZVCOFs achieved an ultrahigh sacrificial photocatalytic hydrogen evolution rate of 2052 μmol h-1 under visible light irradiation with an apparent quantum yield up to 47.1% at 420 nm, superior to nearly all COF-based photocatalysts ever reported. Moreover, the ZVCOFs could be deposited on a support as a photocatalytic film device, which demonstrated a remarkable photocatalytic performance of 402.1 mmol h-1 m-2 for hydrogen evolution.

Density functional theory study the mechanism of two CO* forming *OC-CO on different size of Cun (n = 3 to 20) clusters supported on TiO2

Cun@TiO2 nanocatalytic materials are widely used in experiments to catalyze the reduction of CO2 to hydrocarbon fuels and oxygenated alcohols. However, due to the complexity of the coupling reaction of the Cun@TiO2 catalyst to form key CC bonds to C2 products, it is unclear. In this paper, the density functional theory (DFT) is employed to systematically study the influence of the size of Cun clusters on the CC bond formation with the Cun cluster supporting on the TiO2 surface. It was discovered that the adsorption of Cu metal clusters of different sizes on TiO2 was primarily determined by the bonding of TiO2 oxygen atoms. Subsequently, in the CO*+CO* → COOC* coupling reaction on each different Cun cluster size, we found that the active site was the interface position, when the Cun cluster showed a three-dimensional configuration, with the increase of the Cu cluster, that is, the coordination number increased, the activation energy barrier gradually decreased, and when the coordination of Cu cluster reached saturation, the coupling energy barrier size also stabilized. This work provides new sight of the size of co-catalyst in the CO2 reduction reaction and may guide to synthesis higher efficiency co-catalyst.

Unlocking power of neighboring vacancies in boosting hydrogen evolution reactions on two-dimensional NiPS3 monolayer

This study investigates the effect of defect engineering on the catalytic activity of a NiPS3 monolayer catalyst for the hydrogen evolution reaction (HER). Three different types of vacancies on the basal plane of the monolayer are explored through a multi-step mechanism involving the dissociative adsorption of a water molecule and subsequent electrochemical adsorption of the dissociated proton. Co-formation of vacancies in both Ni and S sites is found to be the most effective in enhancing the catalytic performance of the monolayer. A key resource for the reaction thermodynamics is the S-substitution-like physisorption of a water molecule on a vacant S site, followed by the dissociative occupation of OH and H into vacant sites of S and Ni elements, boosted by the NiS di-vacancy configuration with low activation energy barriers. Investigation reveals the highest contribution of bonding orbitals to the monolayer-H bond makes it the most desirable defect engineering approach for transition metal phosphorus chalcogenides with high HER activities. Overall, this study highlights the significance of controlled defect engineering in augmenting the catalytic performance of NiPS3 monolayer catalysts for HER.

Cooperative adsorption of interfacial Ga-N dual-site in GaOOH@N-doped carbon nanotubes for enhanced electrocatalytic reduction of carbon dioxide

To reduce activation energy barrier and promote the kinetics of electrocatalytic CO2 reduction reaction (eCO2RR), the performance of CO2 adsorption and activation on electrocatalysts should be optimized. Here, GaOOH is successfully coupled with N-doped carbon nanotubes (NC) via a facile self-assembly-calcination process. The obtained GaOOH@N-doped carbon nanotubes (Ga-NC) display the best CO faradaic efficiency of 96.1 % at −0.6 V (vs. reversible hydrogen electrode). Control-experiment and characterization results suggest Ga-N dual-site in interface between GaOOH and NC shows cooperative adsorption of CO2. C atom in CO2 is adsorbed on N site while O atom in CO2 is adsorbed on Ga site. This cooperative adsorption efficiently promotes the CO2 adsorption and activation performance, as well as the breaking of CO bond due to opposite attraction from Ga-N dual-site. Moreover, in-situ Fourier transform infrared spectroscopy confirms decreased reaction barrier for formation of *CO2– and *COOH intermediates. This work inspires us to construct interfacial dual-site structure with cooperative adsorption property for promoting eCO2RR activity.

Fast method for calibrated self-discharge measurement of lithium-ion batteries including temperature effects and comparison to modelling

The self-discharge rate is an important parameter to assess the quality of lithium-ion batteries (LIBs). This paper presents an accurate, efficient, and comprehensive method for measuring and understanding the self-discharge behaviour of LiB cells, considering factors such as temperature and cell to cell variability, as well as underlying electrochemical mechanisms. A method for precise potentiostatic self-discharge measurement (SDM) is demonstrated that is validated by measuring 21 commercial cylindrical 4.7 Ah cells at a state of charge (SoC) of 30%. The self-discharge current ranges between 3 and 6 μA at 23 °C, with an experimental noise level of 0.25 μA. At higher temperatures of 40 °C the self-discharge current increases to 97 μA. The temperature coefficient of voltage (TCV) is experimentally obtained by exposing the cells to a temperature profile with positive and negative step polarities and following the open circuit voltage (OCV) response. Observed TCVs range from +180 µV/K at 40% SoC to −320 µV/K at 0% SoC. For SDM temperature experiments, the cells were set to an SoC with a minimum TCV. From the SDM currents at different temperatures the Arrhenius kinetics and the electrochemical activation energy barrier is determined as 0.94 ± 0.14 eV, indicating chemical side reactions as source of self-discharge. For SDM modelling the electrochemical processes are coupled with a 3D temperature finite element model (FEM) and an electric circuit model resulting in a good overlap with the dynamics and time-constants of the experimental self-discharge curves. The primary challenges addressed are accurately measuring microampere (µA) discharge currents of high-quality cells, reducing measurement time, understanding the temperature dependence of self-discharge, determining activation energy, and demonstrating the applicability and generalization of SDM.

Enriching Metal-Oxygen Species and Phosphate Modulating of Active Sites for Robust Electrocatalytical CO2 Reduction.

Direct electrochemical reduction of CO2 (CO2 RR) into value-added chemicals is a promising solution to reduce carbon emissions. The activity of CO2 RR is influenced deeply by the reaction microenvironment and electronic properties of the catalysts. Herein, the surface PO4 3- anions are tuned to modulate the local microenvironment and the electronic properties of indium-based catalyst with abundant metal-oxygen species enabling efficient electrochemical conversion of CO2 to HCOO- . Indium nanoparticles coupled with PO4 3- anions (PO4 3- -In NPs) achieved a high selectivity of HCOO- up to 91.4% at a low potential of -0.98 V versus reversible hydrogen electrode (vs. RHE), and a high HCOO- partial current density of 279.3 mA cm-2 at -1.1 V vs. RHE in the electrochemical flow cell. In-situ and ex-situ characterizations confirmed the PO4 3- anions kept stable on the surface of indium during CO2 RR, accelerating the generation of OCHO* intermediate. From density functional theory (DFT) calculations, PO4 3- anions enriched the metal-oxygen species on the substrate to optimize the electronic structure of the catalysts and induced a local microenvironment with massive K+ ions on the interface, thus reducing the activation energy barrier of CO2 RR. This article is protected by copyright. All rights reserved.

Coupled Surface-Confinement Effect and Pore Engineering in a Single-Fe-Atom Catalyst for Ultrafast Fenton-like Reaction with High-Valent Iron-Oxo Complex Oxidation.

The nanoconfinement effect in Fenton-like reactions shows great potential in environmental remediation, but the construction of confinement structure and the corresponding mechanism are rarely elucidated systematically. Herein, we proposed a novel peroxymonosulfate (PMS) activation system employing the single Fe atom supported on mesoporous N-doped carbon (FeSA-MNC, specific surface area = 1520.9 m2/g), which could accelerate the catalytic oxidation process via the surface-confinement effect. The degradation activity of the confined system was remarkably increased by 34.6 times compared to its analogue unconfined system. The generation of almost 100% high-valent iron-oxo species was identified via 18O isotope-labeled experiments, quenching tests, and probe methods. The density functional theory illustrated that the surface-confinement effect narrows the gap between the d-band center and Fermi level of the single Fe atom, which strengthens the charge transfer rate at the reaction interface and reduces the free energy barrier for PMS activation. The surface-confinement system exhibited excellent pollutant degradation efficiency, robust resistance to coexisting matter, and adaptation of a wide pH range (3.0-11.0) and various temperature environments (5-40 °C). Finally, the FeSA-MNC/PMS system could achieve 100% sulfamethoxazole removal without significant performance decline after 10,000-bed volumes. This work provides novel and significant insights into the surface-confinement effect in Fenton-like chemistry and guides the design of superior oxidation systems for environmental remediation.

A 2D Ba2N Electride for Transition Metal-Free N2 Dissociation under Mild Conditions.

N2 activation is a key step in the industrial synthesis of ammonia and other high-value-added N-containing chemicals, and typically is heavily reliant on transition metal (TM) sites as active centers to reduce the large activation energy barrier for N2 dissociation. In the present work, we report that a 2D electride of Ba2N with anionic electrons in the interlayer spacings works efficiently for TM-free N2 dissociation under mild conditions. The interlayer electrons significantly boost N2 dissociation with a very small activation energy of 35 kJ mol-1, as confirmed by the N2 isotopic exchange reaction. The reaction of anionic electrons with N2 molecules stabilizes (N2)2- anions, the so-called diazenide, in the large interlayer space (∼4.5 Å) sandwiched by 2 cationic slabs of Ba2N as the main intermediate.

CO2 hydrogenation using MOFs encapsulated PdAg nano-catalysts for formate production

Catalytic hydrogenation of CO2 for the production of formic acid/formate, a valuable commodity and renewable hydrogen carrier, is a promising strategy to achieve an economic andsustainable CO2-mediated hydrogen energy cycle. The rational design of highly active and stable heterogeneous catalysts for CO2 hydrogenation in gas–liquid-solid phase still remains challenging. In this work, we report a series of dual-function catalysts namely PdAg@MIL-101-PEI, where PdAg alloy nanoparticles (NPs) for hydrogen activation and dissociation are encapsulated into MIL-101 supports tethered with CO2 adsorption agent polyethyleneimine (PEI). The optimal PdAg@MIL-101-PEI catalyst displays exceptional performance for CO2 hydrogenation, affording a high turnover number (TON) of 4968 at 120 °C under 8 MPa in 2 h. Thermodynamic and kinetic studies illustrate that Ag incorporation and PEI functionalization dramatically reduce the activation energy barrier of PdAg@MIL-101-PEI catalyst for CO2 hydrogenation. Furthermore, the optimal PdAg@MIL-101-PEI catalyst demonstrates outstanding structural stability and reusability over multiple catalytic cycles. We also propose a reaction mechanism for CO2 hydrogenation through in situ DRIFTS study.