A high-performance PdZn alloy catalyst obtained from metal-organic framework for methanol steam reforming hydrogen production

Methanol steam reforming (MSR) is deemed to be an effective way for hydrogen production and Pd/ZnO catalyst were found to exhibit high activity in this reaction. However, their activities are strongly related to the preparations methods. In most cases, these catalysts are synthesized by impregnation or co-precipitation methods, aiming to change the dispersion and stability of Pd nanoparticle to get better performance. Here we report an efficient Pd/ZnO catalyst that was synthesized with zeolitic imidazolate framework-8 (ZIF-8) as the precursor, on which Pd ions was supported after NaHB₄ reduction. Typically, when the catalyst reduced at 300 °C for 2 h, the methanol conversion could reach 97–98% and the CO₂ selectivity is around 86.3% under the reaction condition of 0.1 MPa, water/CH₃OH = 1.2:1 (mol ratio), WHSV_methanol = 43152ml/g_cat*h, catalyst = 0.1 g, our catalyst was found to show much better performance than other Pd@ZnO catalysts prepared by other methods, especially in terms of selectivity which is particularly important for hydrogen fuel cell application considering that Pt electrode could be poisoned by even trace amount of CO. It turned out that the large surface area, enough holes, evenly distributed PdZn alloy activity sites and abundant oxygen vacancies lead to the overall excellent performance of our catalyst.     

Production of hydrogen from methanol steam reforming using CuPd/ZrO2 catalysts – Influence of the catalytic surface on methanol conversion and CO selectivity

Electricity generation for mobile applications by proton exchange membrane fuel cells (PEMFCs) is typically hindered by the low volumetric energy density of hydrogen. Nevertheless, nearly pure hydrogen can be generated in-situ from methanol steam reforming (MSR), with Cu-based catalysts being the most common MSR catalysts. Cu-based catalysts display high catalytic performance, even at low temperatures (ca. 250 °C), but are easily deactivated. On the other hand, Pd-based catalysts are very stable but show poor MSR selectivity, producing high concentrations of CO as by-product. This work studies bimetallic catalysts where Cu was added as a promoter to increase MSR selectivity of Pd. Specifically, the surface composition was tuned by different sequences of Cu and Pd impregnation on a monoclinic ZrO₂ support. Both methanol conversion and MSR selectivity were higher for the catalyst with a CuPd-rich surface compared to the catalyst with a Pd-rich surface. Characterization analysis indicate that the higher MSR selectivity results from a strong interaction between the two metals when Pd is impregnated first (likely an alloy). This sequence also resulted in better metallic dispersion on the support, leading to higher methanol conversion. A H₂ production rate of 86.3 mmol h^?1 g^?1 was achieved at low temperature (220 °C) for the best performing catalyst.     

PdZn alloys decorated 3D hierarchical porous carbon networks for highly efficient and stable hydrogen production from aldehyde solution

PdZn alloys and Pd catalyst decorated 3D hierarchically porous carbon (HPC) network catalysts were prepared by a facile and simple impregnation/carbonization process from energetic MOFs of MET-6. Due to the high uniformly dispersion of metal nanoparticles and strong metal-support interactions, the as prepared HPC-PdZn catalysts exhibited highly efficient catalytic hydrogen production from formaldehyde solution at room temperature, which is much higher than that of pure Pd nano-particles. By further optimizing the reaction parameters such as reaction temperature, formaldehyde concentrations, and NaOH concentrations, the hydrogen generation rates could be further increased to unprecedented 572.6 mL·min⁻¹ g⁻¹, which was nearly 4 times as much as the solely Pd nanoparticles counterparts. Owing to its high efficiency and stability at room temperature, the as-prepared HPC-PdZn architectures catalyst based hydrogen generation reaction may serve as state-of-the-art candidate in both hydrogen supply and environmental cleaning.     

On-chip growth of patterned ZnO nanorod sensors with PdO decoration for enhancement of hydrogen-sensing performance

In this study, we used a low-temperature hydrothermal technique to fabricate arrays of sensors with ZnO nanorods grown on-chip. The sensors on the glass substrate then were sputter decorated with Pd at thicknesses of 2, 4, and 8 nm and annealed at 650 °C in air for an hour. Scanning electron microscopy, high resolution transmission microscopy, X-ray diffraction, and surface analysis by X-ray photoelectron spectroscopy characterization demonstrated that decoration of homogenous PdO nanoparticles on the surface of ZnO nanorods had been achieved. The sensors were tested against three reducing gases, namely hydrogen, ethanol, and ammonia, at 350, 400, and 450 °C. The ZnO nanorods decorated with PdO particles from the 2 and 4 nm layers showed the highest responses to H₂ at 450 and 350 °C, respectively. These samples also generally exhibited better selectivity for hydrogen than for ethanol and ammonia at the same concentrations and at all tested temperatures. However, the ZnO nanorods decorated with PdO particles from the 8 nm layer showed a reverse sensing behaviour compared with the first two. The sensing mechanism behind these phenomena is discussed in the light of the spillover effect of hydrogen in contact with the PdO particles as well as the negative competition of the PdO thin film formed between the sensor electrodes during sputter decoration, Pd–Zn heterojunction that forms at high temperature and thus influences the conductivity of the ZnO nanorods.     

An ionic liquid-present hydrothermal method for preparing hawthorn sherry ball shaped palladium (Pd)-based composite catalysts for ethanol oxidation reaction (EOR)

For the first time, a hawthorn sherry ball shaped Pd-based composite catalyst for EOR was prepared via an ionic liquid-present two-step hydrothermal method in this work. In the first hydrothermal step, micron-scale solid carbon spheres (MSCS) were fabricated in the presence of glucose, an ionic liquid of 1-butyl-3-methyl tetrafluoroboric acid and one kind of surfactant. And in the second hydrothermal process, sesame like Pd particles were immobilized on the surface of MSCS forming a hawthorn sherry ball shaped Pd-based composite catalyst (denoted as Pd/MSCS) using PdO as the source of Pd. In the course of preparing MSCS, four kinds of surfactants were respectively employed desiring to study the influence of surfactant type on the physicochemical properties of the produced samples. The prepared MSCS and Pd/MSCS were examined majorly by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was addressed by SEM images that in the presence of SDS and EDTA, hawthorn sherry ball shaped Pd-based composite catalysts were successfully prepared. XRD and XPS analysis substantially documented that metallic palladium was the main component of the synthesized Pd/MSCS catalysts. The electrocatalytic abilities of the Pd/MSCS catalysts for EOR were examined in 1 M C₂H₅OH alkaline solution mainly utilizing cyclic voltammetry (CV) and chronoamperometry (CA), illustrating that all produced Pd/MSCS catalysts had an electrocatalytic activity towards EOR, and the forward peak current density of EOR on the catalyst of Pd/MSCS (prepared in the presence of SDS) was 7 times larger, along with 60 mV decrease in the onset potential of EOR, than that on the Pd/MSCS (prepared with CATB) catalyst. Summarily, a very cost-effective and facile method for fabricating hawthorn sherry ball shaped Pd-based composite catalysts towards EOR was created in this work, which was very meaningful not only to the further development of EOR catalysts but also to the exploration of micron-devices.     

Zinc oxide nanorods based catalysts for hydrogen production by steam reforming of methanol

Zinc oxide (ZnO) nanorods were epitaxially grown on porous cordierite support by a hydrothermal process and utilized for catalyzing methanol steam reforming (MSR) reaction. Catalytic activity of ZnO nanorods for MSR process was correlated to the terminated surfaces of ZnO crystallites. Copper (Cu), palladium (Pd) and gold (Au) nanoparticles infused ZnO nanorods were prepared by in-situ precipitation of the metals on the nanorods. 28% hydrogen selectivity was observed with Cu/ZnO nanorods (Cu/10Zn), while Pd/ZnO nanorods and (Pd/10Zn) showed slightly lower activity. Higher catalytic activity of copper and palladium impregnated ZnO nanorods can be attributed to the synergistic combination of bimetallic oxides. In contrast, Au/ZnO nanorods (Au/10Zn) showed very high activity for methanol dehydrogenation and higher than 97% methanol conversion was achieved for operating temperatures as low as 200 °C.     

Effect of the amine group content on catalytic activity and stability of mesoporous silica supported Pd catalysts for additive-free formic acid dehydrogenation at room temperature

A strong metal-support interaction (SMSI) between amine-functionalized silica supports and Pd nanoparticles is one of important factors to determine the catalytic activity of additive-free formic acid dehydrogenation at room temperature over Pd/NH₂-silica catalysts. However, there are few reports on the effect of the content of amine functional groups on the SMSI and catalytic performance for formic acid dehydrogenation. In this study, we tried to maximize the content of amino-propyl groups on the surface of mesoporous silica supports (KIE-6) via hydroxylation of KIE-6 surface before amine functionalization and investigated the effect of the content of amine functional groups on the catalytic activity and stability for formic acid dehydrogenation. As a result, Pd/NH₂-hydroxylated KIE-6 (Pd/NH₂-OH-KIE-6) catalysts with more amine functional groups provided higher initial catalytic activity (595 mol H₂ mol catalyst⁻¹h⁻¹) than Pd/NH₂-KIE-6 catalysts. However, Pd/NH₂-KIE-6 catalysts showed higher catalytic stability in comparison with Pd/NH₂-OH-KIE-6 catalysts. After various characterizations of catalysts, it was demonstrated that the enhanced initial catalytic activity of Pd/NH₂-OH-KIE-6 catalysts is attributed to the higher ratio of Pd/PdO derived from the increased content of amine groups of NH₂-OH-KIE-6 supports. In contrast, the low surface area of NH₂-OH-KIE-6 promoted the aggregation of Pd nanoparticles on Pd/NH₂-OH-KIE-6 catalysts, which resulted in the lower catalytic stability of Pd/NH₂-OH-KIE-6 catalysts than Pd/NH₂-KIE-6 catalysts. Thus it was concluded that confinement of Pd nanoparticles to the pores of supports is a more dominant factor to achieve higher catalytic stability, while the initial catalytic activity is affected by the electronic state of Pd nanoparticle determined by the content of amine functional groups on the surface of supports.     

A comparative study on the performance of mesoporous SBA-15 supported Pd–Zn catalysts in partial oxidation and steam reforming of methanol for hydrogen production

Using mesoporous SBA-15 (Santa Barbara Amorphous No. 15, a mesoporous material) as support, Pd–Zn nanocatalysts with varying Pd and Zn content were tested for hydrogen production from methanol by partial oxidation and steam reforming reactions. The physico-chemical characteristics of the synthesized SBA-15 support were confirmed by XRD, N₂ adsorption, SEM and TEM analyses. The PdZn alloy formation during the reduction of Pd–Zn/SBA-15 was revealed by XRD and DRIFT study of adsorbed CO. Also, the correlation between Pd and Zn loadings and PdZn alloy formation was studied by XRD and TPR analyses. The metallic Pd surface area and total uptakes of CO and H₂ were measured by chemisorption at 35 °C. The metallic Pd surface area values are in linear proportion with the Pd loading. The formation of PdZn alloy during high temperature reduction was confirmed by a shift in absorption frequency of CO on Pd sites to lower frequency due to higher electron density at metal particles resulted from back-donation. The reduced Pd–Zn/SBA-15 catalysts were tested for partial oxidation of methanol at different temperatures and found that catalyst with 4.5 wt% Pd and 6.75 wt% Zn on SBA-15 showed better H₂ selectivity with suppressed CO formation due to the enhanced Pd dispersion as well as larger Pd metallic surface area. The O₂/CH₃OH ratio is found to play a significant role in CH₃OH conversion and H₂ selectivity. The performance of 4.5 wt% Pd–6.75 wt% Zn/SBA-15 catalyst in steam reforming of methanol was also tested. Comparatively, the H₂ selectivity is significantly higher than that in partial oxidation, even though the CH₃OH conversion is less. Finally, the long term stability of the catalyst was tested and the nature of PdZn alloy after the reactions was found to be stable as revealed from the XRD pattern of the spent catalysts.     

High performance formic acid fuel cell benefits from Pd–PdO catalyst supported by ordered mesoporous carbon

Formic acid as a renewable fuel can be converted to clean electricity in fuel cells by high-efficient electrochemical oxidation. The conversion rate is fundamentally dictated by the synergy of interactive aspects: catalytic activity, accessibility to active sites, electron transfer, and anti-poisoning stability. For the first time, ordered mesoporous carbon (OMC) is used as the substrate for Pd–PdO catalyst for fuel cells. The unique ordered pore-channel network of OMC can enhance the spatial dispersion of Pd nanoparticles on the pore-channel wall, while the hollow pore-channel can facilitate reactant transport. Microwave and annealing treatments are found to enhance the chemical reduction and to strengthen the anchoring of Pd–PdO catalyst on OMC substrate, respectively. The OMC supported Pd–PdO catalyst (Pd–PdO/OMC) shows 1.7-fold and an order of magnitude higher mass activity and stability as compared to commercial Pd/C catalyst. For fuel cell testing, the Pd–PdO/OMC catalyst is applied to an air-breathing microfluidic fuel cell and achieves a maximum power density of 63.0 mW cm⁻², at least one-fold higher than similar previous reports.     

Activating the Pd-Based catalysts via tailoring reaction interface towards formic acid dehydrogenation

Formic acid dehydrogenation (FAD) offers an ideal route for hydrogen production, where searching for efficient and selective catalysts is imperative. However, the current state-of-the-art Pd-based metallic catalysts severely suffer from low catalytic efficiency and self-poisoning, owning to the FA dehydration side reaction. In this work, we design PANI-Pd/C composite catalysts via interfacial microenvironment regulation technique. The as-prepared 0.01-PANI-Pd/C catalyst exhibits high turnover frequency (TOF, 5654 h⁻¹) and excellent resistance to CO poisoning. The merit of polyaniline can be ascribed to: a) construction of abundant Pd–PdO interfaces; b) capturing H⁺ and accelerating the formation of the reactive species.     

Synergistic tuning of the phase structure of alumina and ceria-zirconia in supported palladium catalysts for enhanced methane combustion

CeO₂–ZrO₂–Al₂O₃ composite oxides supported palladium catalysts (Pd/CZA) are promising candidates for catalytic oxidation reactions. However, the efficient and stable oxidation of methane over Pd-based catalysts remains a longstanding challenge. Herein, we present a facile strategy to boost the catalytic performance of Pd/CZA through elaborately tuning the phase structure of supports. Calcining supports at relatively high temperatures (1200, 1300 °C) induced the phase transition of alumina (from γ-to α-) and the development of CeO₂–ZrO₂ solid solution (CZ). The weak interaction between α-Al₂O₃ and PdO resulted in an improved reducibility of catalysts. Meanwhile, the higher oxygen mobility originated from well-crystallized CZ phase contributed to the reoxidation of Pd to PdO, giving rise to abundant surface active Pd²⁺ species. Coupled with the hydrophobicity of α-Al₂O₃, the catalyst prepared with CZA supports calcined at 1300 °C demonstrated an excellent low-temperature activity, astounding stability and greatly enhanced water resistance towards methane combustion.     

Catalytic steam reforming of methanol over highly active catalysts derived from PdZnAl-type hydrotalcite on mesoporous silica MCM-48

A kind of composite material PdZnAl(HT)/MCM-48 was synthesized by dispersing PdZnAl-type hydrotalcite (denoted as PdZnAl(HT)) on mesoporous silica MCM-48. PdZnAl(HT) was confirmed to be formed on the MCM-48 in small particles, and the small PdZnAl(HT) particles easily collapsed during increasing the temperature. A kind of novel PdZn(Al)O/MCM-48 catalyst was obtained after calcining and reducing the PdZnAl(HT)/MCM-48 precursor. PdZn alloy species were formed on the PdZnAl(HT)/MCM-48 after reducing in H₂ at 673 K. PdZn(Al)O/MCM-48-2 (with a mass ratio of PdZn(Al)O to MCM-48 = 1) had a large BET surface area (431 cm² g^?1) and small size of PdZn particles (4.1 nm) at the same time. In the steam reforming of methanol, the catalytic stability of PdZn(Al)O/MCM-48-2 was much higher than that of the Cu-based catalyst CuZn(Al)O at 503 K. The methanol conversion over PdZn(Al)O/MCM-48-2 greatly increased with increasing reaction temperature and reached 99% at 513 K. PdZn(Al)O/MCM-48-2 showed higher catalytic activity than PdZnAl(HT) and PdZn/MCM-48 (imp) at the same reaction temperature. The initial CO₂ selectivity and H₂ selectivity over PdZn(Al)O/MCM-48-2 at 503 K were 99.6 and 99.4%, respectively. Moreover, PdZn(Al)O/MCM-48-2 showed the highest rate of H₂ production among various catalysts in the steam reforming of methanol. In a long-time operation, the methanol conversion over PdZn(Al)O/MCM-48-2 decreased from 75.8 to 68.5% after 50 h on stream at 503 K. The size of PdZn particles did not increase after 50 h on stream but the carbonaceous deposits on the catalyst surface caused the deactivation. The deactivated catalyst could be regenerated by calcining in the air at 723 K followed by reducing in the H₂ at 673 K. The carbonaceous deposits were eliminated by calcining in the air and the PdZn active species were formed again by reducing in H₂.     

Comparative study of Pd and PdO as cathodes for oxygen reduction reaction in intermediate temperature solid oxide fuel cells

Metallic Pd and PdO electrodes were prepared by using Pd and PdCl₂ slurries, respectively, and their electrochemical performance as a cathode for oxygen reduction reaction in intermediate temperature solid oxide fuel cells was evaluated by electrochemical impedance spectroscopy (EIS) and direct current polarization (DC polarization). The electrochemical activity of metallic Pd was much higher than that of PdO for the reaction of oxygen reduction; below the decomposition temperature, a thin layer of PdO formed on the surface of metallic Pd electrode, which increased its polarization resistance. The decomposition temperature of PdO decreased from 810 to 750 °C as oxygen partial pressure decreased from 20 to 5 kPa, and was further lowered under the influence of the applied current during DC polarization test. The charge transfer resistance of PdO increased by decreasing oxygen partial pressure, while that of metallic Pd was less sensitive to it.     

In situ reduction of PdO encapsulated in MCM-41 to Pd(0) for dehydrogenation of formic acid

A series of PdO@MCM-41-x was in situ synthesized by a facile one-pot method, and their catalytic performance for dehydrogenation of formic acid was investigated. The PdO nanoparticles were immobilized in MCM-41 channel with small size of 2.2–2.5 nm due to the confinement of mesoporous silica. The initial turnover frequency (TOF) of as-prepared catalyst can reach 1096 h^?1 at 323 K with 100% hydrogen selectivity. The hydrogen production activity was better than that of catalyst priorly reduced by hydrogen because of the gradual reduction of PdO nanoparticles and generation of fresh Pd(0) during the formic acid dehydrogenation process, which was confirmed by XPS characterization and catalytic system monitoring. It provides a new way for the preparation of simple and efficient catalysts for hydrogen production, which has great application potential.     

Promoting effects of pretreatment on Pd/CeO2 catalysts for CO oxidation

CeO₂ supported Pd catalysts were prepared in which the Pd species were presented in form of PdO and Ce_1-xPd_xO_2-δ solid solution. The Pd/CeO₂ catalysts were thermal treated for varying duration and its effect on Pd species was explored. The transformation of Pd species and redispersion were observed under oxidizing conditions at 500 °C. For catalyst treated with 10 h, more Pd ions penetrated into the CeO₂ matrix to form Ce_1-xPd_xO_2-δ solid solution, resulting in a 90% CO conversion at 84 °C after H₂ reduction. Another thermal treatment time extension led to an extraction of Pd from CeO₂ lattice in tandem with higher dispersion and smaller PdO particles on the surface, which was demonstrated by the results of XRD, ICP, TEM images, CO pulse adsorption and CO-TPR as a redispersion phenomenon.     

Highly active carbon nanotube-supported Pd electrocatalyst for oxidation of formic acid prepared by etching copper template method

In this work, a carbon nanotube-supported Pd nano-catalyst (Pd/MCNTs) is prepared by the etching copper template strategy. Cu nanoparticles (NPs) are formed onto MCNTs first as the template and Pd NPs are then obtained through a galvanic displacement reaction between Pd ions and Cu. TEM, XRD, and XPS characterizations show the crystalline of Pd NPs with a typical diameter of 2–5 nm is homogeneously decorated onto MCNTs without aggregation. Electrochemical characterizations reveal that the Pd/MCNTs materials exhibit much higher catalytic activity for the formic acid oxidation than both conventional Pd/MCNTs and commercial Pd/Vulcan catalysts do. The improved activity is mainly attributed the fact that no surfactant is required in synthesis of the catalyst, eliminating the possible passivation of catalytic sites associated with the use of surfactant in conventional synthesis methods. In addition, the narrower distribution and better dispersion of catalyst particles, as well as no defects of MCNTs are also beneficial for the improvement in the catalytic activity. Another feature of the present synthesis method is the loading of Pd can be adjusted by varying the amount of Cu ions.     

Reaction gas treatment promoting activity and stability of PdO for lean methane oxidation over phosphorus modified Pd/Al2O3 catalysts

Pretreatment under specific atmosphere is a general strategy to activate catalysts. How physicochemical properties of supports are modulated during activation process and their influence on active sites are still the ongoing topic. Herein, the effect of reaction gas treatment on performance of phosphorus modified Pd/Al₂O₃ catalysts in lean methane oxidation was studied. The pretreated Pd/P-doped Al₂O₃ catalyst exhibited a full conversion of CH₄ at ∼400 °C, excellent stability under both dry and wet conditions. Characterization results reveal that the uniform and stable P species in Al₂O₃ enhanced the metal-support interaction and availability of oxygen in support. Under reaction gas condition, PdO-support connection was further promoted to favor generation of oxygen vacancies on support with the help of CH₄, leading to weakened Pd–O bond, facile reformation and increased fraction of PdO. These facilitated formation of intermediates and surface dehydroxylation and mitigated the deactivation caused by thermodynamic decomposition of PdO.     

Functionalization of Mn2O3/PdO/ZnO electrocatalyst using organic template with accentuated electrochemical potential toward water splitting

In a broad spectrum of renewable energy technologies, nonprecious, cheap, and robust electrocatalytic material is the fundamental element for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, designing high-efficiency catalysts to match industrial requirements remains a significant challenge. An Efficient and stable OER catalyst [Mn₂O₃/PdO/ZnO] was prepared by a simple and cost-effective facile synthesis approach using metal acetates with the organic extract. The carbonaceous material help in improving the surface area and lowering the band gap energy (2.2 eV) of the Mn₂O₃/PdO/ZnO suggesting the enhanced electrochemical conductivity of synthesized nanomaterial. The catalyst was loaded on Ni-foam and has been tested for Oxyge evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline medium. The material shows higher activity toward OER with a low overpotential and Tafel slope value of 93 mV/dec at a bias of 1.65 V to achieve a current density of 10 mA/cm². The material exhibited an overpotential of 57 mV and Tafel value of 244 mV/dec toward HER which were not much satisfactory. The material offer an overpotential value of 422 mV toward OER which remains consistent even after 2000 cycle in 1M KOH electrolyte. In addition, chronoamperometry test also revealed constant oxygen evolution over 24 hours without any loss in activity. Thus the synthesized bio-fabricated composite material is simple and scalable for widespread use in renewable energy harvesting applications.     

Controllable synthesis of carbon nanofiber supported Pd catalyst for formic acid electrooxidation

Carbon nanofiber (CNF) supported Pd nanoparticles are synthesized with sodium citrate and sodium borohydride served as stabilizing agent and reducing agent, respectively. The size and distribution of the supported Pd nanoparticles are controlled by adjusting the pH value of the synthesis solution. Analyses of the obtained Pd/CNF catalysts indicate that the supported Pd nanoparticles become more uniform in size and the average particle size is decreased from 5.85 to 3.62 nm with pH value of the synthesis solution increasing from 3.2 to 6.0. However, the further increasing of the pH value to 6.5 leads to an increased particle size and the formation of PdO phase in the synthesized Pd/CNF catalyst. The Pd/CNF catalyst synthesized at the pH value of 6.0 exhibits superior catalytic activity and stability for formic acid electrooxidation due to its small particle size and uniform size distribution.     

2-Dimensional metal-organic framework derived N-doped carbon immobilized Pd nanoparticles for hydrogen release from formic acid

Hydrogen release from formic acid is a significant energy supply route. However, the current catalysts suffer from low catalytic efficiency and stability. Herein, a porous N-doped carbon material with high N content (16.87%) and a large surface area (1544 m²·g^?1) were designed using a 2-dimensional metal-organic framework and etching agent potassium chloride. Due to its high N content and large surface area, ultrafine Pd particles are uniformly distributed on the porous N-doped carbon support, which effectively enhances excellent reactivity and enables a TOF value of 2365 h^?1 under additive-free conditions. The research also revealed that the strong interaction between Pd particles and pyridinic-N species can significantly slow metal agglomeration. Hence, the Pd/NC_ZIF-L (KCl) displayed good activity even after 10 cycling experiments, and it is a particularly competitive catalyst for hydrogen release from formic acid.