Hydrogenation Of Intermediates Research Articles

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p‐d Orbital Hybridization Effect with Ru

AbstractTopological defects are inevitable existence in carbon‐based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under‐explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon‐rings is probed by constructing pentagonal ring‐rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p‐d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron‐deficient Ru species leads to a notable negative shift in d‐band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm−2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm−2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Operando Stable Palladium Hydride Nanoclusters Anchored on Tungsten Carbides Mediate Reverse Hydrogen Spillover for Hydrogen Evolution

AbstractProton exchange membrane (PEM) electrolysis holds great promise for green hydrogen production, but suffering from high loading of platinum‐group metals (PGM) for large‐scale deployment. Anchoring PGM‐based materials on supports can not only improve the atomic utilization of active sites but also enhance the intrinsic activity. However, in practical PEM electrolysis, it is still challenging to mediate hydrogen adsorption/desorption pathways with high coverage of hydrogen intermediates over catalyst surface. Here, operando generated stable palladium (Pd) hydride nanoclusters anchored on tungsten carbide (WCx) supports were constructed for hydrogen evolution in PEM electrolysis. Under PEM operando conditions, hydrogen intercalation induces formation of Pd hydrides (PdHx) featuring weakened hydrogen binding energy (HBE), thus triggering reverse hydrogen spillover from WCx (strong HBE) supports to PdHx sites, which have been evidenced by operando characterizations, electrochemical results and theoretical studies. This PdHx‐WCx material can be directly utilized as cathode electrocatalysts in PEM electrolysis with ultralow Pd loading of 0.022 mg cm−2, delivering the current density of 1 A cm−2 at the cell voltage of ~1.66 V and continuously running for 200 hours without obvious degradation. This innovative strategy via tuning the operando characteristics to mediate reverse hydrogen spillover provide new insights for designing high‐performance supported PGM‐based electrocatalysts.

Built-in electric field-driven electron transfer behavior at Ru-RuP2 heterointerface fosters efficient and CO-resilient alkaline hydrogen oxidation

Exploiting a cost-effective electrocatalyst for hydrogen oxidation reaction (HOR) with high-performance and CO poisoning resistance is essential for the widespread application of alkaline anion exchange membrane fuel cells (AEMFCs). Herein, we craft a unique Ru-RuP2 heterostructure within hollow mesoporous carbon sphere (Ru-RuP2@C) using phosphide-controlled phase-transition approach. Benefiting from the interfacial electron transfer from RuP2 to Ru, the Ru-RuP2@C electrocatalyst exhibits impressive HOR performance with a mass activity of 2.87 mA μgRu−1. Notably, Ru-RuP2@C demonstrates strong tolerance to 1000 ppm CO, a capability lacking in PtRu/C and Pt/C. When serves as an anode catalyst for AEMFC, it achieves a peak power density of 521 mW cm−2, comparable to Pt/C. Experimental and theoretical analyses reveal that the built-in electric field, resulting from work function differences, creates an asymmetric charge distribution that modulates the d-band center of Ru-RuP2@C. This optimizes the adsorption strength of hydrogen and hydroxide intermediates, thereby accelerating HOR catalytic kinetics.

New Insights for High-Throughput CO2 Hydrogenation to High-Quality Fuel.

In the case of CO2 thermal-catalytic hydrogenation, highly selective olefin generation and subsequent olefin secondary reactions to fuel hydrocarbons in an ultra-short residence time is a huge challenge, especially under industrially feasible conditions. Here, we report a pioneering synthetic process that achieves selective production of high-volume commercial gasoline with the assistance of fast response mechanism. In situ experiments and DFT calculations demonstrate that the designed NaFeGaZr presents exceptional carbiding prowess, and swiftly forms carbides even at extremely brief gas residence times, facilitating olefin production. The created successive hollow zeolite HZSM-5 further reinforces aromatization of olefin diffused from NaFeGaZr via optimized mass transfer in the hollow channel of zeolite. Benefiting from its rapid response mechanism within the multifunctional catalytic system, this catalyst effectively prevents the excessive hydrogenation of intermediates and controls the swift conversion of intermediates into aromatics, even in high-throughput settings. This enables a rapid one-step synthesis of high-quality gasoline-range hydrocarbons without any post-treatment, with high commercial product compatibility and space-time yield up to 0.9 kggasoline ⋅ kgcat -1 ⋅ h-1. These findings from the current work can provide a shed for the preparation of efficient catalysts and in-depth understanding of C1 catalysis in industrial level.

Tuned targeted catalytic engineering enables high-selective electrochemical low-concentration nitrate-to-ammonia

Electrocatalytic nitrate reduction reaction (NO3RR) is anticipated to enable utilization of NO3- from wastewater, providing a prospective solution to address global nitrogen-cycle imbalance. Nevertheless, high-selective conversion of low-concentration NO3--to-NH3 in non-alkaline environment remains challenging, stemming from kinetic retardation and hydrogen evolution reaction (HER). Herein, a targeted synergistic-cascade strategy is proven for breaking through the bottleneck. Significantly, the rationally-designed asymmetric oxygen vacancies (VO)-mediated Cu-Co dual-site catalyst achieve a NH3 selectivity of 95.79 % and a NH3-N yield of 1.528 mg h−1 cm−2 under 140 ppm NO3--N environment. The mitigation of kinetic bottlenecks is attributed to the NO3- activation capability of Cu sites and intermediate hydrogenation of Co sites on the optimized cascade catalytic system. Density functional theory (DFT) reveals that the asymmetric VO fine-tuned the electronic structure and d-band center of Cu-Co dual-sites, which synergistically reduce the energy barrier of NO3RR and alleviate the competing HER. An integrated system is constructed for the in situ conversion of NO3- to ammonium sulfate under low NO3--N concentration water body, showcasing the potential for practical application.

First-Principles Calculations and Machine Learning of Hydrogen Evolution Reaction Activity of Nonmetallic Doped β-Mo2C Support Pt Single-Atom Catalysts.

The most widely used catalyst for the hydrogen evolution reaction (HER) is Pt, but the high cost and low abundance of Pt need to be urgently addressed. Single-atom catalysts (SACs) have been an effective means of improving the utilization of Pt atoms. In this work, we used a nonmetal (NM = B, N, O, F, Si, P, S, Cl, As, Se, Br, Te, and I) doped β-Mo2C (100) C-termination surface as the support, with Pt atoms dispersed on the support surface to construct Pt@NM-Mo2C. Using density functional theory (DFT) calculations, we selected catalysts with excellent HER activity. Among 117 candidate catalysts, 49 catalysts exhibited ideal catalytic performance with Gibbs free energy of hydrogen intermediate (H*) adsorption (ΔGH*) values less than 0.2 eV. The ΔGH* values of 16 catalysts were even lower than that of Pt (ΔGH* ≈ 0.09 eV), with PtI@N2/4-a-Mo2C demonstrating the best performance (ΔGH* = -0.01 eV). Combined with electronic structure analysis, we could understand the impact of charge transfer between Pt and the underlying NM atoms on the strength of the Pt-H bond, thereby promoting HER activity. Using machine learning (ML), we identified that the primary influencing factors of the HER catalytic activity in the Pt@NM-Mo2C system were the Bader charge transfer of Pt (NePt), the d-band center of Pt (εdPt), and the atomic radius of NM (RNM), with NePt having the greatest impact on the HER catalytic activity.

Lithium ion battery-assisted solar-driven water splitting

Electrocatalytic water splitting is an efficient strategy to substitute traditional fossil fuels with renewable energy H2. However, its scalable implementation, especially outdoors, has been hindered due to the lack of highly efficient and stable electrocatalysts and high-cost external electricity from the power grid. Here, we develop a hybrid nanostructure comprising N-doped carbon nanotube (NCNT) covalent-linked cobalt disulfide nanoparticles (CoS2-NPs) confined in hollow carbon nanocages (h-CoS@NC). As a bifunctional electrocatalyst for overall water splitting, the multi-heterostructure exhibits superior catalytic activities towards both hydrogen and oxygen-containing intermediates. Inspiringly, a two-electrode electrolyzer combined with the multi-heterostructure realizes a current density of 10 mA cm−2 at a low cell voltage of 1.58 V. When employing an anode of lithium ion battery (LIB), the h-CoS@NC delivers a high specific capacity of 1040 mAh g−1 at 0.1 A g−1 and maintains a considerable capacity of 648 mAh g−1, especially at rate of 5 A g−1. Furthermore, a large capacity of 582 mAh g−1 is achieved at 0.1 A g−1 for sodium ion battery. Moreover, theoretical calculations interpret that the enhanced electrochemical activities of h-CoS@NC should be attributed to the interaction between the CoS2 and carbon matrix, which effectively regulates the local electronic structures and weakens water adsorption/dissociation energies. As a proof-of-concept, a self-powered water splitting system integrating solar-charged lithium-ion battery with a water splitting electrolyzer achieves a steady H2 evolution rate at 0.4 A.

In Situ Surfaced Mn-Mn Dimeric Sites Dictate CO Hydrogenation Activity and C2 Selectivity over MnRh Binary Catalysts.

Massive ethanol production has long been a dream of human society. Despite extensive research in past decades, only a few systems have the potential of industrialization: specifically, Mn-promoted Rh (MnRh) binary heterogeneous catalysts were shown to achieve up to 60% C2 oxygenates selectivity in converting syngas (CO/H2) to ethanol. However, the active site of the binary system has remained poorly characterized. Here, large-scale machine-learning global optimization is utilized to identify the most stable Mn phases on Rh metal surfaces under reaction conditions by exploring millions of likely structures. We demonstrate that Mn prefers the subsurface sites of Rh metal surfaces and is able to emerge onto the surface forming MnRh surface alloy once the oxidative O/OH adsorbates are present. Our machine-learning-based transition state exploration further helps to resolve automatedly the whole reaction network, including 74 elementary reactions on various MnRh surface sites, and reveals that the Mn-Mn dimeric site at the monatomic step edge is the true active site for C2 oxygenate formation. The turnover frequency of the C2 product on the Mn-Mn dimeric site at MnRh steps is at least 107 higher than that on pure Rh steps from our microkinetic simulations, with the selectivity to the C2 product being 52% at 523 K. Our results demonstrate the key catalytic role of Mn-Mn dimeric sites in allowing C-O bond cleavage and facilitating the hydrogenation of O-terminating C2 intermediates, and rule out Rh metal by itself as the active site for CO hydrogenation to C2 oxygenates.

Highly efficient hydrogenation of CO2 to heavy hydrocarbons via NaFeGa catalysts

Transforming CO2 into heavy hydrocarbons via thermal catalytic hydrogenation has garnered interest for its potential to address resource shortages and reduce atmospheric CO2. In this research, NaFeGa catalysts enriched with Ga additives were synthesized by the coprecipitation method. Various characterization techniques, including Mössbauer spectroscopy, were employed alongside reverse water-gas shift and Fischer-Tropsch synthesis experiments to elucidate the Fe-Ga interaction. This interaction effectively modulated the ratio of active sites Fe5C2 and enhanced CO species adsorption. The Ga additive's anti-hydrogenation effect limited intermediate hydrogenation, leading to increased carbon-hydrogen product yields. The catalyst underwent direct hydrogenation of CO2 under high throughput conditions (space velocity of 50,000 h−1), resulting in efficient CO2 conversion as well as remarkable heavy hydrocarbon selectivity. The catalyst demonstrated a remarkable heavy hydrocarbon space-time yield (STY) of 1460.2 g·kgcat−1·h−1, surpassing the threshold for commercial viability and offering a promising solution for large-scale production of liquid fuels from CO2.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p-d Orbital Hybridization Effect with Ru.

Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Factors Affecting the Formation and Transformation of the Intermediates in Pd(II)-Catalyzed Aromatic C-H Activation: A Comprehensive Study with the Pd(II)/LA Platform.

How the factors affecting the formation and transformation of the intermediates in Pd(II)-catalyzed aromatic C-H activation: A comprehensive study with the Pd(II)/LA platform. Using the Pd(II)/Lewis acid (LA)-catalyzed C-H activation of electron-rich acetanilides as a platform, the C-H activation intermediates, including the precomplex η2-intermediate, the agostic hydrogen intermediate, and the palladacycle compound have been well-characterized. This work presents how the catalyst source, substrate, and solvent affect the formation of the η2-intermediate and its equilibrium with the agostic hydrogen intermediate, and the transformation of the agostic hydrogen intermediate to the palladacycle compound through C-H activation. The findings disclosed above are provided as a guideline for the catalyst design of the oxidative olefination of acetanilide with dioxygen, and the catalytic efficiency matched well with the mechanistic findings.

Rhenium-promoter-free ruthenium–zirconia catalyst for high-yield direct conversion of succinic acid to 1,4-butanediol in water

The direct conversion of succinic acid to 1,4-butanediol (1,4-BDO) in water was investigated using Ru deposited on oxygen-vacant zirconia (Ru–OvZrOx) as the catalyst. 1,4-BDO was produced in high yield (89.5 %) and space–time yield (0.19 h−1) at 200 °C. The proximity of Ru to OvZrOx stabilized the nanosized Ru0 particles, enabled hydrogen spillover, increased the acidity of the catalyst, and achieved intermediate adsorption. The Zrδ+ center (2 ≤ δ < 4)—which featured abundant Lewis acid sites and was adjacent to the Ov sites—activated the γ-butyrolactone ring-opening reaction via a route involving 2-hydroxytetrahydrofuran formation. The electron-rich Ru0 center facilitated heterolytic hydrogen dissociation, and the dissociated H– and H+ ions traveled to the Zrδ+ sites and water molecules via hydrogen-shuttling mechanism. Moreover, the weakly bonded hydrogen actively participated in the hydrodeoxygenation and hydrogenation of intermediates to 1,4-BDO.

Synergistically flexible-robust effects mediate the dynamic reconfiguration of perylene diimide polymer to enhance piezo-photocatalytic nitrate reduction

Identifying the spatial dynamic reconstruction of π-conjugated polymers for efficient carrier transport and controlling the intermediate process of the reaction are urgent and formidable challenges. In this study, a fresh perspective has emerged proposing to synergistically enhance the adaptability and resilience of dynamic torsion patterns in π-conjugated polymers to mediate charge separation and molecular activation. Excitingly, the highest flexible-robust structure and polarity of naphthalene-linked perylene diimide polymer (N-PDA) demonstrates a highest nitrate reduction rate of 5.36 mmol g−1 h−1 under light irradiation and ultrasonic condition, which is 7.5 times that of H-PDA. Theoretical calculations and experimental observations indicate that the strongest flexible-robust structure of N-PDA enhances the inclination of the rigid plane and atomic bond length, resulting in an accelerated uneven distribution of charges, molecular polarity, and electronic coupling to facilitate charge separation dynamics. Moreover, it exposes active sites that promote the adsorption and activation of NO3- ions while simultaneously regulating intermediate hydrogenation processes. Our study offers innovative prospects for enhancing catalytic efficiency through the implementation of spatial steric configuration of π-conjugated polymers.

Modulating local coordination structure over single Pt atom to optimize adsorption behavior for high-efficiency photocatalytic H2 production

The development of single-atom photocatalysts featuring precisely defined coordination structure is of great significance for elucidating the correlations between catalytic performances and coordination structures, yet it remains a grand challenge. Herein, the asymmetric/symmetric Pt-Nx moieties in carbon nitride (denoted as Pt-Nx@MCT, x equals to a coordination number of 3 or 4) are elaborately constructed by a coordination structure regulation strategy. The hydrogen production performances of Pt-N3@MCT and Pt-N4@MCT photocatalysts display a relationship with the Pt-N coordination numbers, with Pt-N3@MCT showing a photocatalytic activity (195 μmol h−1) 3 times that of Pt-N4@MCT (65 μmol h−1) and an apparent quantum yield of 34.1 % at 420 nm. The asymmetric Pt-N3 moiety in Pt-N3@MCT acts as electron collector to promote the separation and transfer of charge carriers and to create the higher occupied Pt d orbital, weakening the bond strength between hydrogen intermediates and Pt atomic sites and accelerating hydrogen production reaction kinetics in Pt-N3@MCT.

Construction of Ru-doped Co nanoparticles loaded on carbon nanosheets in-situ grown on carbon nanofibers as self-supported catalysts for efficient hydrogen evolution reaction

Exploring efficient and economical electrocatalysts to replace noble metal electrocatalysts has become a major research focus nowadays. In this paper, Ru-doped Co nanoparticles loaded on carbon nanosheet (CNS) in-situ grown on carbon nanofibers (Ru–Co@CNS/CNFs) were constructed as a self-supporting working electrode for high-efficiency hydrogen evolution. The prepared Ru–Co@CNS/CNFs possessed excellent catalytic activity with only 78 mV overpotential at 10 mA cm−2 current density and good stability with only 102 mV voltage attenuation at 100 mA cm−2 current density for 100 h continuous operation. The excellent catalytic performance could be attributed to the unique microstructure of the nanosheets in-situ grown on the nanofibers, it resulted in a higher Co surface density of 1.28 mg cm−2, indicating more loading of metal to improve catalytic activity of HER, and the formed Ru-doped Co nanoparticles could be evenly distributed on the carbon nanosheets to prevent the aggregation of nanoparticles, which could expose more active sites. Additionally, the density functional theory (DFT) calculations revealed Ru doping could accelerate the dissociation of water, optimize the adsorption energy of hydrogen intermediates and improve the kinetics of the HER reaction. This work provides a new approach to reduce the use of noble metals while improving the catalytic performance of catalysts.

Highly effective Pt-Pd/ZSM-22 catalysts prepared by the room temperature electron reduction method for the n-hexadecane hydroisomerization

The development of highly effective bifunctional catalysts for n-hexadecane hydroisomerization is still essential to produce second-generation biodiesel. Herein, a Pt-Pd/ZSM-22-G (abbreviated as Pt-Pd/Z22-G) bimetallic catalyst was prepared by employing a room temperature electron reduction (RTER) method with glow discharge as the electron source. As a contrast, a series of Pt/Z22-H, Pd/Z22-H and Pt-Pd/Z22-H catalysts were prepared by the conventional hydrogen reduction method. The Pt-Pd/Z22-G catalyst reveals more exposed metal sites, larger CMe/CH+ values and an enhanced distribution of Pt-Pd(111) facets compared with the Pt/Z22-H, Pd/Z22-H and Pt-Pd/Z22-H catalysts. These modifications are originated from the stronger electron interactions and the smaller metal nanoparticles because of the effects of highly energetic reducing electrons. The n-hexadecane hydroisomerization results show that the iso-hexadecane yield over the Pt-Pd/Z22-G catalyst is 82.9%, which is the highest among four investigated catalysts in this work. This phenomenon occurs because more exposed Pt-Pd(111) facets and larger CMe/CH+ ratios are beneficial for the adsorption and hydrogenation of iso-alkene intermediates at metal sites to increase the iso-alkanes yield based on density functional theory (DFT) calculations. Furthermore, the iso-alkanes yield over the Pt-Pd/Z22-G catalyst also keeps steady after long-term tests for 120 h because of the limited metal aggregation and carbon deposition.

Highly efficient nanosized MoS2/MoP heterocatalyst for enhancing hydrogen evolution reaction over a wide pH range

Energy consumption associated with the catalysts contributes partly to the high ohmic resistance arising from the low conductivity of the catalyst and poor charge transfer between nanoparticles, which has been difficult to study due to the complicated nanostructured framework of the catalysts. We constructed a novel heterostructure electrocatalyst (MoS2/MoP@NC) composed of nanosized MoS2/MoP heterostructures anchoring on hierarchical N-doped carbon for smoothing electron transfer in boosting hydrogen evolution reaction (HER). With the merits of large surface area, rapid charge transfer, and optimized electronic structure induced by charge transfer across the sufficient interface, the optimal MoS2/MoP@NC (MoSP) catalyst shows a competitive overpotential of 140 (0.5 M H2SO4), 76 (1.0 M KOH), and 103 mV (0.5 M NaCl &1.0 M KOH) at 10 mA cm−2, respectively. Raman experiment and Density functional theory (DFT) calculations reveal the formation of Mo-S-Mo bonds between MoS2 and MoP, which favor enhancing the Femi level to facilitate the electron transfer, therefore regulating the electronic structure for the optimization of adsorption energy of hydrogen intermediate. Based on the experimental results, we constructed an energy consumption model of catalysts, where energy consumption comes from three aspects. The heterostructure design decreases the energy consumption of the catalysts greatly compared to the single-phase Mo-based catalyst of MoS2 (78.0%) and MoP (45.2%) in alkaline electrolytes.

Electrodeposition strategies for synthetic highly dispersed Ru-decorated Co(OH)2 nanoneedles as advanced hydrogen evolution reaction catalysts

Ru-based nanomaterials have a lot of potential as electrochemical hydrogen evolution reaction (HER) catalysts; however, achieving a uniform dispersion of Ru nanoparticles on substrate materials remains a key challenge. To achieve this, in the current study, we formed NF/Co(OH)2/Ru by electrodepositing Ru nanoparticles onto Co(OH)2 nanoneedles. The Co and O vacancies in the sample promoted water decomposition and the cleavage of O-H bonds, while the high surface energies at the apexes of the Co(OH)2 nanoneedles supported the even growth and attachment of Ru nanoparticles. In addition, the electron-rich Ru nanoparticles aided in the desorption of hydrogen intermediates. Compared to recently published Ru-based HER materials, the NF/Co(OH)2/Ru material created in this study shown improved electrochemical characteristics, with an overpotential of 20 mV at 10 mA·cm−2 and a Tafel slope of 35.43 mV·dec−1. Therefore, this material and the findings of this study are expected to contribute to HER research.

Building Electrochemical Roadmaps for Decarbonization in the Specialty Chemical Sector

Greenhouse gas emissions from the chemical manufacturing industry are enormous, by some estimates they amount to 5% percent of the global total.1,2 Moreover, chemical manufacturing is widely considered as a “difficult-to-decarbonize” sector due to the deeply entrenched reliance on crude-based hydrocarbons as fuels and feedstocks.3 The ultimate goal of eliminating anthropogenic greenhouse gas emissions, clearly demands a wholesale reconsideration of energy and material flows in chemical manufacturing.One area of research that has gained momentum in the past decade is the use of electrochemistry to perform organic redox reactions. These types of electrosynthetic transformations provide a straightforward means to electrify chemical manufacturing, thereby decreasing the global warming impact as the carbon intensity of grid electricity diminishes with continued adoption of low-carbon power sources. Further improvements are achievable through decarbonization of material inputs, e.g., by replacing problematic redox reagents like methane-derived hydrogen or fuming nitric acid with reactive hydrogen and oxygen intermediates generated at electrodes via water electrolysis.Despite these promising advances, interest in organic electrosynthesis to date has mainly focused on the production of commodity chemicals (e.g., CO2 reuse, ammonia electrosynthesis) at the expense of specialty chemical synthesis. This focus is well justified based on the possible impact of major breakthroughs on global emissions, but it constitutes missed opportunities to drive broad adoption of electrosynthesis across the chemical industry. To address this knowledge gap, our lab has undertaken a collaborative research effort with a global specialty chemical manufacturer to explore opportunities to decarbonize through electrification strategies involving electrosynthetic reaction schemes.This presentation will detail our recent work on a holistic “scoping study” to estimate the potential for reducing the global warming emissions profiles for a representative set of specialty chemicals through the adoption of electrosynthetic methods. First, we mapped the supply chain for 12 specific chemicals (chosen for their relevance to the specialty industry and significant global warming potential from current production methods) in terms of all reactive processes required to generate these compounds from petrochemical feedstocks. Next, we searched for literature reports detailing electrosynthetic pathways to generate each intermediate species along the manufacturing supply chain. The relevant electrochemical reactions were broadly classifiable as (a) generating alternatives to petrochemical feedstocks; (b) direct replacement of an existing chemical redox reaction with an electrochemical reaction; or (c) intensified approaches that use electrochemistry to reduce the total number of reactive process steps required. Finally, we benchmarked the potential for reduced greenhouse gas emissions for electrosynthetic schemes compared to the incumbent technologies based on a set of simplifying assumptions that involve calculating baseline emissions intensities as a function of the thermodynamic minimum energy input and the carbon intensity of the electric power supply, and further applying generic “efficiency factors” to account for all emissions in excess of this thermodynamic minimum. The results of this analysis suggest remarkable opportunities to develop electrosynthetic schemes for a handful of reactions for which global warming emissions could be reduced even in the most conservative scenarios of low process efficiency and high carbon intensity of the input power.This presentation will also cover the hurdles we have identified in the development of modular and continuously operated electrosynthetic reactors, as well as what we have learned in addressing these challenges.References(1) Saygin, D.; Gielen, D. Zero-Emission Pathway for the Global Chemical and Petrochemical Sector. Energies 2021, 14 (13), 3772. https://doi.org/10.3390/en14133772.(2) Gabrielli, P.; Rosa, L.; Gazzani, M.; Meys, R.; Bardow, A.; Mazzotti, M.; Sansavini, G. Net-Zero Emissions Chemical Industry in a World of Limited Resources. One Earth 2023, 6 (6), 682–704. https://doi.org/10.1016/j.oneear.2023.05.006.(3) Gross, S. The Challenge of Decarbonizing Heavy Industry, 2021. https://www.brookings.edu/wp-content/uploads/2021/06/FP_20210623_industrial_gross_v2.pdf.

Molybdenum and Vanadium-Codoped Cobalt Carbonate Nanosheets Deposited on Nickel Foam as a High-Efficient Bifunctional Catalyst for Overall Alkaline Water Splitting.

To address issues of global energy sustainability, it is essential to develop highly efficient bifunctional transition metal-based electrocatalysts to accelerate the kinetics of both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, the heterogeneous molybdenum and vanadium codoped cobalt carbonate nanosheets loaded on nickel foam (VMoCoCOx@NF) are fabricated by facile hydrothermal deposition. Firstly, the mole ratio of V/Mo/Co in the composite is optimized by response surface methodology (RSM). When the optimized composite serves as a bifunctional catalyst, the water-splitting current density achieves 10 mA cm-2 and 100 mA cm-2 at cell voltages of 1.54 V and 1.61 V in a 1.0 M KOH electrolyte with robust stability. Furthermore, characterization is carried out using field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) calculations reveal that the fabricated VMoCoCOx@NF catalyst synergistically decreases the Gibbs free energy of hydrogen and oxygen-containing intermediates, thus accelerating OER/HER catalytic kinetics. Benefiting from the concerted advantages of porous NF substrates and clustered VMoCoCOx nanosheets, the fabricated catalyst exhibits superior electrocatalytic performance. This work presents a novel approach to developing transition metal catalysts for overall water splitting.