HCOOH Dehydrogenation Research Articles

Transition metal single atom anchored C3N for highly efficient formic acid dehydrogenation: A DFT study

Formic acid (HCOOH) is a promising hydrogen carrier. Developing efficient and low-cost catalysts is significant for the application of HCOOH in clean and renewable energy. In this work, a series of single-atom catalysts composed of twelve transition metal single atoms (Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag and Au) supported on a novel carbon-nitrogen material (C3N) were designed and the catalytic performance for HCOOH dehydrogenation was demonstrated using density functional theory. By evaluating the binding strength of TM atoms, the adsorption stability of HCOOH and the hydrogen evolution performance of H species, Ni@C3N, Pd@C3N and Pt@C3N were finally screened out as candidates, on which the HCOO-dehydrogenation pathway is the most preferred. Judging from energetic span, Pd@C3N (0.60 eV) owns the best catalytic activity, while Ni@C3N (1.02 eV) and Pt@C3N (1.12 eV) are also appreciable alternatives compared with Pd(111) (1.23 eV). Through the analysis of catalytic mechanism and electronic structure, the factors influencing reaction activity were revealed. This work enlightens the advantage of C3N-based materials and provides a novel approach for rationally designing high-performance catalysts for hydrogen production from HCOOH.

Boosting electrocatalytic oxidation of formic acid on SnO2-decorated Pd nanosheets

Formic acid (HCOOH), as a natural biomass, is a promising feedstock for low temperature fuel cells, and rational development of efficient catalysts for electrochemical dehydrogenation of HCOOH plays a key role toward its full chemical energy utilization. Herein, Pd nanosheets decorated with SnO2 nanoflakes (denoted hereafter as Pd@SnO2-NSs) are designed as a composite catalyst, showing superior performance for formic acid electro-oxidation, as compared to pristine Pd nanosheets (Pd-NSs). In situ attenuated total reflection infrared (ATR-IR) spectroscopic results suggest a promoted formate pathway on the Pd@SnO2-NSs with a suppressed accumulation of CO poisoning species. DFT calculations further indicate that the Pd (111) surface modified with SnO2 has lower energy barriers for the bidentate formate formation, the bidentate to monodentate formate transformation and the C-H bond scission.

A Use-Store-Reuse (USR) Concept in Catalytic HCOOH Dehydrogenation: Case-Study of a Ru-Based Catalytic System for Long-Term USR under Ambient O2

Commercial use of H2 production catalysts requires a repeated use/stop/store and reuse of the catalyst. Ideally, this cycle should be possible under ambient O2. Herein we exemplify the concept of Use-Store-Reuse (USR) of a (Ru-phosphine) catalyst in a biphasic catalytic system, for H2 production via dehydrogenation of HCOOH. The catalytic system can operate uninterrupted for at least four weeks, including storage and reuse cycles, with negligible loss of its catalytic efficiency. The catalytic system consisted of a RuP(CH2CH2PPh2)3 (i.e. RuPP3) in (tri-glyme/water) system, using KOH as a cocatalyst, to promote HCOOH deprotonation. In a USR cycle of 1 week, followed by storage for three weeks under ambient air and reuse, the system achieved in total TONs > 90,000 and TOFs > 4000 h−1. Thus, for the first time, a USR concept with a readily available stable ruthenium catalyst is presented, operating without any protection from O2 or light, and able to retain its catalytic performance.

PdO/Pd0/TiO2 Nanocatalysts Engineered by Flame Spray Pyrolysis: Study of the Synergy of PdO/Pd0 on H2 Production by HCOOH Dehydrogenation and the Deactivation Mechanism

Palladium-based catalysts are among the most efficient for H2 production via HCOOH (FA) dehydrogenation at near-ambient pressure and temperature. Herein, we show that [PdO/Pd0/TiO2] nanocatalysts b...

Modulating oxygen coverage of Ti3C2Tx MXenes to boost catalytic activity for HCOOH dehydrogenation

As a promising hydrogen carrier, formic acid (HCOOH) is renewable, safe and nontoxic. Although noble-metal-based catalysts have exhibited excellent activity in HCOOH dehydrogenation, developing non-noble-metal heterogeneous catalysts with high efficiency remains a great challenge. Here, we modulate oxygen coverage on the surface of Ti3C2Tx MXenes to boost the catalytic activity toward HCOOH dehydrogenation. Impressively, Ti3C2Tx MXenes after treating with air at 250 °C (Ti3C2Tx-250) significantly increase the amount of surface oxygen atoms without the change of crystalline structure, exhibiting a mass activity of 365 mmol·g−1·h−1 with 100% of selectivity for H2 at 80 °C, which is 2.2 and 2.0 times that of commercial Pd/C and Pt/C, respectively. Further mechanistic studies demonstrate that HCOO* is the intermediate in HCOOH dehydrogenation over Ti3C2Tx MXenes with different coverages of surface oxygen atoms. Increasing the oxygen coverage on the surface of Ti3C2Tx MXenes not only promotes the conversion from HCOO* to CO2* by lowering the energy barrier, but also weakens the adsorption energy of CO2 and H2, thus accelerating the dehydrogenation of HCOOH.

HCOOH Decomposition on Sub-Nanometer Pd6 Cluster Catalysts: The Effect of Defective Boron Nitride Supports Through First Principles

The catalytic properties of a hexagonal boron nitride- (h-BN) supported Pd6 sub-nanometer cluster in the context of formic acid (HCOOH) decomposition were studied by means of periodic Density Functional Theory (DFT) calculations. The effect of support defectivity – boron (h-BvN) and nitrogen (h-BNv) monovacancies – on the competition between the formate (HCOO)- and carboxyl (COOH)-mediated decomposition pathways was analyzed. Defects are responsible for charge-transfer leading to a positively or negatively charged cluster, and open new reactive channels in which vacancy-mediated dehydrogenation pathways can occur. Pd6 cluster reconstructions, induced by the adsorption of reaction intermediates and by the presence of monovacancies in the support, greatly stabilize the formation of CO from COOH, which could drastically decrease the selectivity towards hydrogen production. A simplified descriptor-based analysis, based on selected thermochemical quantities calculated on charged cluster models, suggests that Pd6 sub-nanometer clusters supported on pristine h-BN and h-BNv can be more selective than Pd6 supported on defective h-BvN towards HCOOH dehydrogenation.

Hybrid Pd38 nanocluster/Ni(OH)2-graphene catalyst for enhanced HCOOH dehydrogenation: First principles approach

Hydrogen energy is a potential next-generation energy source for fossil fuel replacement. The development of high-efficiency materials and catalysts for storage and transportation of hydrogen energy must be achieved to realize hydrogen economy. Recently, catalyst systems such as Pd nanoclusters (Pd NCs) supported on nickel hydroxide (Ni(OH)2) have been reported to have advantages, including effective suppression of CO production and efficiency enhancement of HCOOH dehydrogenation. However, the reaction mechanism and multi-metallic interface system design of such systems have not been elucidated. Therefore, various Ni(OH)2 surfaces supported on a graphene system were designed through density functional theory calculations, and the support material was combined with Pd38NC (Pd38NC/Ni(OH)2-G). Subsequently, the adsorption behavior of HCOOH dehydrogenation intermediates was analyzed. We found a new adsorption configuration in which HCOOH* (where * and a single underline indicates the adsorbed species and adsorbed atom, respectively) was adsorbed in a more stable manner (adsorption energy, Eads= −1.22eV) on the system than HCOOH* (Eads=−1.10eV) owing to the presence of Ni(OH)2-G. This affected the next step in HCOOH dehydrogenation, i.e., formation of HCOO* species, and showed a positive effect on the HCOOH dehydrogenation. To fundamentally understand this phenomenon, electronic structure (d-band center and density of states) and stability (vacancy formation energy) analyses were performed.

NH3 plasma synthesis of N-doped activated carbon supported Pd catalysts with high catalytic activity and stability for HCOOH dehydrogenation

Plasma is a simple and effective method to prepare N-doped carbon materials and supported metal catalysts. In this work, Pd/C–C(NH3) and Pd/C–P(NH3) catalysts are prepared by heat treatment and cold plasma methods using Ar and NH3 as the working gas. The activity and stability of obtained catalysts are tested by formic acid dehydrogenation reaction. The results show that TOFinitial of Pd/C–P(NH3) is 527.1 h−1 at 50 °C, and the HCOOH decomposition rate is about 89.2% at 4 h. The hydrogen production of Pd/C–P(NH3) when used in first and third cycle are 1.14 and 1.14 times than that of Pd/C–C(NH3), and 1.24 and 13.24 times than that of commercial Pd/C. Various characterization techniques are used to characterize the structure of the prepared Pd/C catalysts. The results indicate that NH3 plasma is milder than NH3 thermal treatment. The high activity and stability of Pd/C–P(NH3) are mainly due to the NH3 cold plasma effectively achieving N-doping of the carbon support, and Pd nanoparticles with a small size and high dispersion. Atmospheric pressure NH3 cold plasma provides an effective method to prepare high-performance Pd/C catalysts for HCOOH dehydrogenation and plays a guiding role in the preparation of high-performance carbon-supported noble metal catalysts.

Double-ligand Fe, Ru catalysts: A novel route for enhanced H2 production from Formic Acid

Catalytic Ru- or Fe-complexes bearing two ligands L1, L2, where L1 = phosphine and L2 = Schiff-base ligand, present remarkable H2 production efficiency from Formic Acid (FA) than their single-ligand counterparts. The optimum L1RuL2 and L1FeL2 catalysts were obtained using a phosphine = P(CH2CH2PPh2)3 (or PP3) as L1 and a Schiff-base ligand (abbreviated Lγ herein) as L2, while the using of amino functionalized nanoparticle H2N@SiO2 as cocatalyst further promotes the H2 production efficiency. In long term stability experiments [RuPP3Lγ]/H2N@SiO2 and [FePP3Lγ]/H2N@SiO2 achieve a total TONs >17,367 and >29,372 respectively without deactivation. Thermodynamic and spectroscopic data reveal a common catalytic mechanism for both Fe and Ru based systems, involving synergism between L1, L2 in order to promote the rate-limiting steps. The present work is the first example of “double-ligand catalyst” concept as a novel route for high-efficiency, HCOOH dehydrogenation catalysts, which can be operative for either noble-metal or earth-abundant metals.

Formation and stabilization of colloidal ultra-small palladium nanoparticles on diamine-modified Cr-MIL-101: Synergic boost to hydrogen production from formic acid

Ultra-small nano-sized palladium particles were successfully stabilized within the pores of diamine groups grafted open metal site metal-organic frameworks of Cr-MIL-101; coordinated diamine groups of ethylene diamine (ED) and propyl diamine (PD) on the active site of chromium units of Cr-MIL-101. The physiochemical properties of the Pd@Cr-MOFs were investigated using FTIR, XRD, SEM/EDX mapping, TEM, BET, and AAS. The Cr-MIL-101 stabilized ultra-small Pd nanoparticles, Pd@(ethylene diamine)/Cr-MIL-101, and Pd@(propyl diamine)/Cr-MIL-101, displayed catalytic activity for clean dehydrogenation of formic acid and generation of hydrogen at room temperature. The resultant Pd@ED/Cr-MIL-101 catalyst indicates high catalytic activity with turnover frequency (TOF) of 583 h−1 at 328 K, which is superior to most of the reported catalysts, including Pd@PD/Cr-MIL-101 with TOF 532 h−1. Our studies open up a new method to the design of an ultra-small metal nanoparticle for the catalytic dehydrogenation of HCOOH.

Insights into the mechanism of formic acid dehydrogenation on Pd-Co@Pd core-shell catalysts: A theoretical study

The decomposition mechanism of formic acid on three Pd-based core-shell catalysts PdxCoy@Pd(1 1 1) (x:y = 1:3, 1:1 and 3:1) and pure Pd(1 1 1) surfaces has been systematically studied by periodic density functional theory (DFT) calculations. The possible dehydrogenation and dehydration pathways through the HCOO, COOH and HCO intermediates have been identified. It is found that the most favorable dehydrogenation pathways on Pd1Co3@Pd(1 1 1) and PdCo@Pd(1 1 1) are the COOH-mediated pathway, which are different from the HCOO-mediated pathway on Pd3Co1@Pd(1 1 1) and Pd(1 1 1). The increase of Co content in the Pd-Co core inhibits HCOOH dehydrogenation, but promotes the H-H coupling to form H2, and improves the anti-CO poisoning ability of the catalysts. Accordingly, three bimetallic PdxCoy@Pd catalysts exhibit better overall catalytic activity and product selectivity toward H2 + CO2 than pure Pd(1 1 1), especially PdCo@Pd(1 1 1) has the best catalytic performance for HCOOH decomposition. The present calculations show that a suitable Co composition in Pd-Co core plays an important role in tuning the catalytic performance, which provides a theoretical guideline to design high performance bimetallic core-shell catalysts for other dehydrogenation reactions.

Enhanced Activity of C2N-Supported Single Co Atom Catalyst by Single Atom Promoter.

The remarkable chemical activity of metal single-atom catalysts (SACs) lies in their unique electronic states associated with the low-coordination nature of single-atom sites. Yet, electronic state manipulation normally requires direct contact with other atoms, which inevitably changes the low-coordination environment. Herein, we found by first-principle calculations that the activity of a Co SAC for HCOOH dehydrogenation is appreciably enhanced via electronic state manipulation by a noncontact single atom promoter. A Co atom and a Sn/Ge/Pb atom are anchored in the same cavity of a graphitic C2N monolayer. Surprisingly, the nonbonded promoter makes two far splitting spin states of Co almost degenerate via charge redistribution of C2N support. Further, the high-spin Co gives a remarkably low reaction barrier comparable to Pt or Pd catalysts. Our results demonstrate that the activity of a SAC can be tuned via a noncontact promoter, casting new insights into electronic state modulation of SACs on graphene-like support.

Anchoring Pt Single Atoms on Te Nanowires for Plasmon-Enhanced Dehydrogenation of Formic Acid at Room Temperature.

Formic acid (HCOOH), as a promising hydrogen carrier, is renewable, safe, and nontoxic. However, the catalytic dehydrogenation of HCOOH is typically conducted at elevated temperature. Here, HCOOH decomposition is successfully achieved for hydrogen production on the developed Pt single atoms modified Te nanowires with the Pt mass loading of 1.1% (1.1%Pt/Te) at room temperature via a plasmon‐enhanced catalytic process. Impressively, 1.1%Pt/Te delivers 100% selectivity for hydrogen and the highest turnover frequency number of 3070 h−1 at 25 °C, which is significantly higher than that of Pt single atoms and Pt nanoclusters coloaded Te nanowires, Pt nanocrystals decorated Te nanowires, and commercial Pt/C. A plasmonic hot‐electron driven mechanism rather than photothermal effect domains the enhancement of catalytic activity for 1.1%Pt/Te under light. The transformation of HCOO* to CO2 δ −* on Pt atoms is proved to be the rate‐determining step by further mechanistic studies. 1.1%Pt/Te exhibits tremendous catalytic activity toward the decomposition of HCOOH owing to its plasmonic hot‐electron driven mechanism, which efficiently stimulates the rate‐determining step. In addition, hot electrons generated by the Te atoms nearby Pt single atoms are regarded to directly inject into the reactants adsorbed and activated on Pt single atoms.

Atmospheric-pressure dielectric barrier discharge cold plasma for synthesizing high performance Pd/C formic acid dehydrogenation catalyst

Abstract HCOOH is a cheap, non-toxic, ease of storage and transportation, and abundant renewable source for generating hydrogen. Activated carbon supported palladium (Pd/C) catalysts have drawn increasing research interest due to their high performance toward HCOOH dehydrogenation and ease of recycle after deactivation. In this work, atmospheric-pressure (AP) dielectric barrier discharge (DBD) cold plasma has been employed to synthesize Pd/C-P catalyst by using PdCl2 as Pd precursor. For comparison, commercial Sigma-Aldrich Pd/C catalyst is adopted as the reference. Both cold plasma synthesized Pd/C-P and commercial Pd/C catalysts exhibit high performance for HCOOH dehydrogenation, and no CO is detected. The total volume of generated H2 and CO2 over Pd/C-P is 317 ml, which is 1.12 times as that of commercial Pd/C (282 ml). The catalytic stability of Pd/C-P is much superior to the commercial Pd/C catalyst. Catalytic activity of Pd/C-P has been decreased to 59.6% and 50.2% after the second and third reaction cycle, respectively, in comparison with the first cycle. However, they have been decreased to 16.3% and 8.9%, respectively, for commercial Pd/C. Various characterization techniques have been adopted to discuss the influence mechanism. The high catalytic activity of Pd/C-P is mainly attributed to the small size of Pd nanoparticles. The high catalytic stability of Pd/C-P is ascribed to the strong metal-support interaction induced by cold plasma and HNO3 pre-oxidation treatment, which leads to less decrease in Pd/C atomic ratio, Pd leaching, and stabilizes the size of Pd nanoparticles. In conclusion, the Pd/C-P catalyst exhibits much higher catalytic activity and stability than the commercial Pd/C, which has theoretical significance and practical application value.

Bio-mimetic self-assembled computationally designed catalysts of Mo and W for hydrogenation of CO2/dehydrogenation of HCOOH inspired by the active site of formate dehydrogenase

Density functional theory modelling has been used to design Mo and W-based catalysts MoIII(tBu)(CO) and WIII(tBu)(CO) for CO2 hydrogenation and HCOOH dehydrogenation, which are bio-mimics of the active site of formate dehydrogenase. Based on DFT calculations, the molybdenum and tungsten based complexes are good catalysts in the +3 oxidation state for CO2 hydrogenation with free energies of 24.03 and 21.31 kcal mol-1, respectively. Such a low barrier indicates that our newly designed Mo and W-based complexes are very efficient for CO2 hydrogenation or HCOOH dehydrogenation catalysis. Overall, our computational results provide in depth insights that can serve as a great tool for the design and development of new and efficient molybdenum and tungsten based catalysts for CO2 hydrogenation or HCOOH dehydrogenation.

A PdAg-CeO2nanocomposite anchored on mesoporous carbon: a highly efficient catalyst for hydrogen production from formic acid at room temperature

Herein, CeO2-modified PdAg alloy nanocomposites were anchored on mesoporous carbon, showing exceedingly high catalytic activity for HCOOH dehydrogenation at room temperature.

Enhanced hydrogen selectivity from catalytic decomposition of formic acid over FeZnIr nanocatalyst at room temperature

Hydrogen is considered a promising energy carrier for the future, especially for clean energy generation via fuel cell technologies. Formic acid is one of the prominent sources of clean and cheap hydrogen. In this work, Fe–Zn–Ir nanocatalysts show exceptional performance for selective hydrogen production via HCOOH decomposition, offering a promising alternative that could solve issues associated with hydrogen storage and distribution. Our results show that Fe atoms on the Fe–Zn–Ir surface are responsible for activating the HCOOH molecules; however, the identity of the surface metal atoms (Ir and Zn) dictate the selectivity of the reaction adjacent to the Fe atoms when there is no CO contamination. The high content of Fe atoms that reside at the Fe–Zn–Ir interface sites favored the dehydrogenation of HCOOH. The greater selectivity towards H2 was measured to be 97.4% at 30 min for the higher Fe content (50 wt%). These observations suggest that by controlling the arrangement of surface Fe, Zn, and Ir atoms, the reactivity and selectivity of HCOOH decomposition over Fe–Zn–Ir catalysts could be tailored, optimizing the surface composition. The findings in this study may prove informative for the rational design of Fe–Zn–Ir catalyst systems for reactions associated with hydrogen production, such as for fuel cell applications.

Mechanistic Studies on NaHCO3 Hydrogenation and HCOOH Dehydrogenation Reactions Catalysed by a FeII Linear Tetraphosphine Complex.

We present a theoretical extension of the previously published bicarbonate hydrogenation to formate and formic acid dehydrogenation catalysed by FeII complexes bearing the linear tetraphosphine ligand tetraphos-1. The hydrogenation reaction was found to proceed at the singlet surface with two competing pathways: A) H2 association to the Fe-H species followed by deprotonation to give a Fe(H)2 intermediate, which then reacts with CO2 to give formate. B) CO2 insertion into the Fe-H bond, followed by H2 association and subsequent deprotonation. B was found to be slightly preferred with an activation energy of 22.8 kcal mol-1 , compared to 25.3 for A. Further we have reassigned the Fe-H complex, as a Fe(H)(H2 ), which undergoes extremely rapid hydrogen exchange.

C2N-supported single metal ion catalysts for HCOOH dehydrogenation

Polarized charges on dual-reactive centers of C2N-supported single-atom based transition metal ion catalysts promoting HCOOH dehydrogenation.

Greatly changed performance of a metal Pd catalyst by a rather easily formed and removed species–PdHx

Some Pd atoms in metal Pd catalyst can adsorb hydrogen element to form PdHx species under normal conditions during catalyst preparation and catalytic reaction, which boosts HCOOH dehydrogenation (FAD) to produce H2, but greatly poisons the chemical reduction by FAD.