Dehydrogenation Of Formic Acid Research Articles

Impact of graphitic carbon nitrides synthesized from different precursors on Schottky junction characteristics.

Graphitic carbon nitride (g-CN) has gained wide interest in many areas, such as energy and the environmental remediation as a layered polymeric semiconductor that allows the formation of catalytically active Schottky junctions due to its proper electronic band structure. Interestingly, although it is known that the precursors used in the synthesis, can influence the properties of the g-CN, no detailed study on these effects on Schottky junctions could be found in the literature. In this research, the effects of g-CNs synthesized by thermal polycondensation of different precursors on the photocatalytic efficiency of Schottky junctions were investigated. For this purpose, urea, thiourea, melamine, and guanidine hydrochloride were used as different precursors, while the photocatalytic dehydrogenation of formic acid was used as a test reaction. The Schottky junctions were formed by decorating the as-prepared g-CNs with AgPd alloy nanoparticles (NP), which were synthesized by reduction of Ag and Pd salts with NaBH4. The structural, electronic and charge carrier dynamics of all prepared structures have been fully characterized by TEM, XRD, BET, XPS, UV-Vis DRS, PL, and PL life measurements. The results showed that the charge transfer dynamics of g-CNs surface defects are more effective in the photocatalytic performance of Schottky junctions than in structural features such as the size of the metal NPs or the surface area of the catalysts.

Robust hydrogen production from HCOOH over amino-modified KIT-6-confined PdIr alloy nanoparticles

Formic acid (FA), which can be produced via CO2 reduction and biomass conversion, has received extensive interest as a convenient and safe hydrogen carrier due to its wide range of sources, renewable, high hydrogen content (4.4 wt%), and convenient storage/transportation. Designing highly efficient catalysts is the main challenge to realize the hydrogen production from FA. In this work, well-dispersed and electron-rich PdIr alloy nanoparticles with a size of 1.8 nm are confined in amino-modified 3D mesoporous silica KIT-6 and applied as a highly efficient catalyst for robust hydrogen production from FA at ambient temperature. Small PdIr alloy nanoparticles confined by amino-modified KIT-6 (PdIr/KIT-6-NH2) lead to better catalytic activity compared to that of Pd/KIT-6-NH2 and PdIr confined by bare KIT-6, achieving a high turnover frequency (TOF) value of 3533 h−1 at ambient temperature (303 K), 100% H2 selectivity and conversion toward the dehydrogenation of FA, which is comparable to the best heterogeneous catalysts ever reported. The high catalytic activity of PdIr/KIT-6-NH2 can be attributed to the synergistic effect between Pd and Ir, strong interaction between PdIr and KIT-6-NH2, as well as the amino-groups of KIT-6-NH2 which can act as a proton scavenger to promote the breaking of O-H bond of formic acid.

Disclosing the Role of Gold on Palladium – Gold Alloyed Supported Catalysts in Formic Acid Decomposition

AbstractHerein, we report the synthesis of preformed bimetallic Pd‐Au nanoparticles supported on carbon nanofibers with different Pd : Au atomic ratio (nominal molar ratio: 8–2, 6–4, 4–6, 2–8) and the corresponding Pd and Au monometallic catalysts by sol immobilization method. The obtained materials were characterized thoroughly by Transmission Electron Microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP‐OES). The catalytic performances of the Pd‐Au catalysts were evaluated in the aqueous phase dehydrogenation of formic acid (FA) at room temperature obtaining enhanced activity, stability and selectivity compared to the monometallic systems. In particular, Pd6Au4 and Pd8Au2 showed the best combination of catalytic properties, i. e., high selectivity to H2 and improved catalytic stability. Density functional theory (DFT) calculations on Pd15, Au15 and Pd9Au6 clusters supported on a carbon sheet were then simulated to provide atomic level understanding to the beneficial effect of gold observed in the experimental results. Au15 barely adsorb FA, while Pd15 possesses an adsorption energy higher than Pd9Au6. Dehydrogenation and dehydration pathways were followed on all these models. For Pd9Au6, the most favourable route was the formation of carbon dioxide and hydrogen. Analysis of the electronic structures was also performed on the different models showing a stronger interaction between the bimetallic system and the support proving the alloy superior stability.

Pd nanoparticles immobilized on aniline-functionalized MXene as an effective catalyst for hydrogen production from formic acid

A simple wet chemical method was used to prepare two-dimensional transition metal carbides (MXene); PDA-MXene was prepared by alkalization of p-phenylenediamine (PDA) on MXene. And further, Pd metal nanoparticles (NPs) were conveniently loaded on the surface to catalyze the dehydrogenation of formic acid. The as-prepared Pd/PDA-MXene catalyst for the formic acid dehydrogenation was characterized by XRD, IR, TEM, and XPS. Pd-NPs with a size of about 4 nm were formed upon the PDA-MXene support surface and were well dispersed. The Pd/PDA-MXene exhibited good catalytic activity in the formic acid decomposition process without any additives, and the turnover frequency value at 50 °C was 924.4 h−1, which is comparable to most of the reported noble metal catalysts under similar conditions. It is worth mentioning that the prepared catalyst maintained good catalytic activity in five consecutive catalytic cycles of the formic acid dehydrogenation experiment.

NiCoP nanoparticles anchored on CdS nanorods for enhanced hydrogen production by visible light-driven formic acid dehydrogenation

Photocatalytic dehydrogenation of formic acid (FA), HCOOH→H2+CO2, is a promising strategy for hydrogen production. Although tremendous efforts have been made, developing efficient and robust system driven by visible light without noble metal still remains a huge challenge. Herein, we report for the first time the use of NiCoP nanoparticles anchored on CdS nanorods (NiCoP@CdS NRs) as a highly efficient and robust catalyst for photocatalytic FA dehydrogenation. NiCoP nanoparticles as cocatalyst can effectively separate the electron-hole pairs generated by CdS NRs. The H2 production rate of the NiCoP@CdS nanorods reached ~354 μmol mg−1 h−1 under visible light irradiation (λ > 420 nm) and the apparent quantum yield (AQY) was ~45.5 % at 420 nm which are among the best values ever reported in photocatalytic FA dehydrogenation systems. This work provides a prospective strategy for developing noble-metal-free photocatalytic FA dehydrogenation systems and hydrogen-based energy applications.

Schiff Base Conjugated Carbon Nitride-Supported PdCoNi Nanoparticles for Enhanced Formic Acid Dehydrogenation

Schiff Base Conjugated Carbon Nitride-Supported PdCoNi Nanoparticles for Enhanced Formic Acid Dehydrogenation

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Formic acid dehydrogenation attained by Pd nanoparticles-based catalysts supported on MWCNT-C3N4 composites

In this study, we developed Pd nanoparticles-based catalysts supported on composites formed by multi-walled carbon nanotubes (MWCNTs) and graphitic carbon nitride (g-C3N4) in various proportions, for their use in the dehydrogenation of formic acid in the liquid phase. It was observed that the composition of the support determined the average size of the Pd nanoparticles as well as their electronic properties, which ultimately affected the performance of Pd/MWCNT-C3N4 catalysts. Among assessed, the catalyst with 63 wt. % of C3N4 exhibited the best activity, with an initial TOF value of 4258 h-1 calculated based on the surface Pd atoms.

Controllable Synthesis of Supported PdAu Nanoclusters and Their Electronic Structure-Dependent Catalytic Activity in Selective Dehydrogenation of Formic Acid.

We report the design and synthesis of uniform PdAu alloy nanoclusters immobilized on diamine and graphene oxide-functionalized silica nanospheres. The structure-dependent activity for selectively catalytic dehydrogenation of formic acid (FA) has been evaluated and optimized by controlling the Pd/Au mole ratio and the carrier components. The relationship between the catalyst structure and activity has been investigated via both experiments and characterization. High-resolution transmission electron microscopy (TEM) and X-ray diffraction (XRD) proved the formation of PdAu alloy nanoclusters. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) analyses verified the electron transfer between Au, Pd, and the support. An outstanding turnover frequency (TOF) value of 16 647 h-1 at 323 K, which is among the highest activity for FA dehydrogenation ever reported, can be achieved at optimized conditions and ascribed to the combination of the bimetallic synergistic effect and the carrier effect.

Deciphering the Mechanistic Details of Manganese-Catalyzed Formic Acid Dehydrogenation: Insights from DFT Calculations.

A comprehensive density functional theory investigation has been carried out to unravel the complete mechanistic landscape of aqueous-phase formic acid dehydrogenation (FAD) catalyzed by a pyridyl-imidazoline-based Mn(I) catalyst [Mn(PY-NHIM)(CO)3Br], which was recently reported by Beller and co-workers. The computed free energy profiles show that for the production of a Mn-formate intermediate [Mn(HCO2-)], a stepwise mechanism is both kinetically and thermodynamically favorable compared to the concerted mechanism. This stepwise mechanism involves the dissociation of a Br- ion from a Mn-bromide complex [Mn(Br)] to create a vacant site and coordination of water solvent to this vacant site, followed by the dissociative exchange of the aqua ligand with the formate ion to form Mn(HCO2-). Non-covalent interaction analysis revealed that the steric hindrance at the transition state is the cardinal reason for the preference to a stepwise mechanism. The β-hydride elimination process was estimated to be the rate-determining step with a barrier of 19.0 kcal/mol. This confirms the experimental observation. The generation of a dihydrogen-bound complex was found to occur through the protonation of Mn-hydride by a hydronium ion instead of formic acid. The mechanistic details and insights presented in this work would promote future catalytic designing and exploration of earth-abundant Mn-based catalytic systems for potential applications toward FAD.

Strong Metal-Support Interaction for 2D Materials: Application in Noble Metal/TiB2 Heterointerfaces and their Enhanced Catalytic Performance for Formic Acid Dehydrogenation.

Strong metal-support interaction (SMSI) is a phenomenon commonly observed on heterogeneous catalysts. Here, direct evidence of SMSI between noble metal and 2D TiB2 supports is reported. The temperature-induced TiB2 overlayers encapsulate the metal nanoparticles, resulting in core-shell nanostructures that are sintering-resistant with metal loadings as high as 12.0 wt%. The TiOx -terminated TiB2 surfaces are the active sites catalyzing the dehydrogenation of formic acid at room temperature. In contrast to the trade-off between stability and activity in conventional SMSI, TiB2 -based SMSI promotes catalytic activity and stability simultaneously. By optimizing the thickness and coverage of the overlayer, the Pt/TiB2 catalyst displays an outstanding hydrogen productivity of 13.8mmol g-1 cat h-1 in 10.0 m aqueous solution without any additive or pH adjustment, with >99.9%selectivity toward CO2 and H2 . Theoretical studies suggest that the TiB2 overlayers are stabilized on different transition metals through an interplay between covalent and electrostatic interactions. Furthermore, the computationally determined trends in metal-TiB2 interactions are fully consistent with the experimental observations regarding the extent of SMSI on different transition metals. The present research introduces a new means to create thermally stable and catalytically active metal/support interfaces for scalable chemical and energy applications.

Yolk-shell silica dioxide spheres @ metal-organic framework immobilized Ni/Mo nanoparticles as an effective catalyst for formic acid dehydrogenation at low temperature

The novel catalyst with yolk-shell SiO2 NiMo/SiO2 spheres immobilized by zeolitic imidazolate framework (ZIF-67) materials has been successfully prepared. The experimental results indicated that the prepared catalyst exhibits superior performance for hydrogen generation from Formic acid (FA) dehydrogenation without any additives at low temperatures. The catalytic performances of the NixMo1−x/ZIF-67@SiO2 yolk-shell increased with Ni addition ratio increasing. In this research, Ni0.8Mo0.2/ZIF-67@SiO2 yolk-shell could provide the highest catalytic conversion efficiency. This is due to the uniform dispersion of fine metal nanoparticles (NPs) and synergistic effect between the NiMo NPs and ZIF-67@SiO2 supporter. The turn over frequency (TOF) value was approximately 13,183 h−1 at 25 °C through complete FA conversion. H2 selectivity was also approximately 100% with obvious CO-free hydrogen production at 25 °C. Meanwhile, the prepared NiMo/ZIF-67@SiO2 yolk-shell catalyst also shows superior catalytic stability with corresponding 99% activity after 10 cycles. In summary, the catalyst preparation and hydrogen generated from FA dehydrogenation obtained from this research could provide the important information for application in catalyst innovation and waste FA recycling and recovery in the future.

Highly Efficient Dehydrogenation of Formic Acid over Binary Palladium-Phosphorous Alloy Nanoclusters on N-Doped Carbon.

Highly efficient dehydrogenation of formic acid (FA) at room temperature is a safe and suitable way to obtain hydrogen and promote the development of hydrogen storage application. Herein, the phosphorous-alloyed Pd nanoclusters loading on nitrogen-doped carbon (PdP/NC) were prepared and recognized as the highly active nanocatalysts for the dehydrogenation of FA. The PdP/NCs with controlled sizes and compositions were prepared by an easy self-limiting synthesis in an aqueous solution. The best PdP/NC exhibited a remarkable catalytic activity with a high turnover frequency of ∼3253.0 h-1 than the compared nanocatalysts for the dehydrogenation of FA at room temperature. The catalytic kinetics and durability studies showed that both the alloyed P in Pd crystals and doped N in the carbon support could effectively tailor the electronic states of the Pd surface and further optimize the adsorption energy of FA. Based on the Sabatier principle, the proper adsorption energy accelerated the dehydrogenation reaction and correspondingly enhanced the activity and durability. The work proposed a high-efficiency nanocatalyst for safe hydrogen generation and may be extended to create other similar nanocatalysts with different compositions and nanostructures.

Cold plasma for preparation of Pd/C catalysts toward formic acid dehydrogenation: Insight into plasma working gas

Cold plasma has been proved to be an efficient method for synthesizing high performance Pd/C catalysts. However, the influence mechanism is still in obscure. In this work, the influence of cold plasma working gas, including air, Ar, O2 and H2, on the structure and performance of the Pd/C catalysts were investigated. Formic acid (HCOOH) dehydrogenation was selected as a probe reaction to investigate the performance of the Pd/C catalysts, and the catalytic activity of the catalysts follows the order: Pd/C-H2P > Pd/C-ArP > Pd/C-AirP ≈ Pd/C-O2P. The Pd/C-H2P catalyst possessed the highest activity, and the TOFinitial was as high as 552.4 h−1. The discharge parameters indicated that few micro discharge channels were generated in H2 plasma, and the power of a single-channel discharge is high. It facilitates the migration of the Pd active species from the pores to the outer surface of the support, and the mean size of the Pd nanoparticles were 2.6 ± 1.0 nm. In addition, the atomic ratio of Pd/C and the content of metallic Pd in Pd/C-H2P, determined by XPS, were as high as 0.0229 and 50.8%, respectively. These are beneficial to the reaction, and ensured the highest catalytic activity of the Pd/C-H2P catalyst. In contrast, the discharge in Ar plasma was mild and the regulation effect was not as strong as that in H2 plasma. Therefore, the catalytic activity of Pd/C-ArP was inferior to Pd/C-H2P. In addition, since there was a severe ablation of the carbon support and agglomeration of Pd nanoparticles in O2 plasma and air plasma, both of Pd/C-O2P and Pd/C-AirP exhibited poor catalytic activity toward HCOOH dehydrogenation.

Formic Acid Dehydrogenation for Hydrogen Production Promoted by Grubbs and Hoveyda‐Grubbs Catalysts†

Main observation and conclusionIn this work, we screened three Grubbs catalysts and two Hoveyda‐Grubbs catalysts for the production of H2 by dehydrogenation of formic acid (FA). The best results were achieved with the use of a first‐generation Hoveyda‐Grubbs catalyst. With a catalyst loading of mere 0.5 μmol, a maximum TON of 36356 was obtained within 3 h. Two key intermediates were identified by using 1H NMR and high‐resolution electrospray ionization mass spectroscopy (HRESI‐MS), based on which a mechanism possibly responsible for the observed catalysis was proposed.

Pd nanoparticles supported on CeO2 nanospheres as efficient catalysts for dehydrogenation from additive-free formic acid at low temperature

Pd nanoparticles (NPs)-based catalysts were synthesized, characterized, and used to efficiently catalyze hydrogen generation from formic acid (FA). A facile deposition–precipitation (DP) method was employed to synthesized Pd*CeO2 catalysts with the assistance ofpolyvinylpyrrolidone(PVP)as asurfactant. The Pd NPs were uniformly dispersed on the surface of CeO2 nanospheres to form × wt% Pd*CeO2 catalysts with various Pd loading amount (x = 0.5, 1, 3, 5, 10). The structural, morphological, surface properties were comprehensively investigated by various techniques including XRD, N2 adsorption–desorption, FE-SEM, HRTEM, XPS, Raman, H2-TPR and ICP-MS. In particular, the Strong Metal-Support Interactions (SMSI) located at the interface between the active Pd NPs and the CeO2 support has been demonstrated through direct observations of hydrogen spillover phenomena and several advanced characterizations. With the increase of Pd loading, the catalytic efficiency of Pd*CeO2 catalysts was also improved. The prepared 10 wt% Pd*CeO2 catalyst exhibited the highest activity towards dehydrogenation of additive-free formic acid at 313 K, corresponding to an initial turn over frequency as high as 807.7 h−1. The superior performance of 10 wt% Pd*CeO2 could be attributed to the high dispersion of Pd NPs, more electron-rich Pd active sites and of course the SMSI between Pd and CeO2.

Formic Acid as a Potential On-Board Hydrogen Storage Method: Development of Homogeneous Noble Metal Catalysts for Dehydrogenation Reactions.

Hydrogen can be used as an energy carrier for renewable energy to overcome the deficiency of its intrinsically intermittent supply. One of the most promising application of hydrogen energy is on-board hydrogen fuel cells. However, the lack of a safe, efficient, convenient, and low-cost storage and transportation method for hydrogen limits their application. The feasibility of mainstream hydrogen storage techniques for application in vehicles is briefly discussed in this Review. Formic acid (FA), which can reversibly be converted into hydrogen and carbon dioxide through catalysis, has significant potential for practical application. Historic developments and recent examples of homogeneous noble metal catalysts for FA dehydrogenation are covered, and the catalysts are classified based on their ligand types. The Review primarily focuses on the structure-function relationship between the ligands and their reactivity and aims to provide suggestions for designing new and efficient catalysts for H2 generation from FA.

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.

CdS Nanorods Anchored with Crystalline FeP Nanoparticles for Efficient Photocatalytic Formic Acid Dehydrogenation.

Photocatalytic dehydrogenation of formic acid is a promising strategy for H2 generation. In this work, we report the use of crystalline iron phosphide (FeP) nanoparticles as an efficient and robust cocatalyst on CdS nanorods (FeP@CdS) for highly efficient photocatalytic formic acid dehydrogenation. The optimal H2 evolution rate can reach ∼556 μmol·h-1 at pH 3.5, which is more than 37 times higher than that of bare CdS. Moreover, the photocatalyst demonstrates excellent stability; no significant decrease of the catalytic activity was observed during continuous testing for more than four days. The apparent quantum yield is ∼54% at 420 nm, which is among the highest values obtained using noble-metal-free photocatalysts for formic acid dehydrogenation. This work provides a novel strategy for designing highly efficient and economically viable photocatalysts for formic acid dehydrogenation.

Palladium-based bimetallic catalysts for highly selective semihydrogenation of alkynes using ex situ generated hydrogen

Semihydrogenation of alkynes to alkenes is an important and fundamental reaction in many industrial and synthetic applications and often suffers low selectivity because of the overhydrogenation. Here, highly selective semihydrogenation of alkynes is achieved by using H2 ex situ generated from formic acid dehydrogenation with palladium (Pd)-based bimetallic catalysts through a two-chamber reactor in this work, realizing efficient utilization of H2 and selective production of alkenes under mild reaction conditions. The Pd-based bimetallic catalysts show excellent catalytic performances for semihydrogenation of alkynes (PdZn bimetallic catalyst) and dehydrogenation of formic acid (PdAg bimetallic catalyst) in the two-chamber reactor.