Adsorption Energies Of Intermediates Research Articles

Modulating the D-Band Center of Electrocatalysts for Enhanced Water Splitting.

To tackle the global energy scarcity and environmental degradation, developing efficient electrocatalysts is essential for achieving sustainable hydrogen production via water splitting. Modulating the d-band center of transition metal electrocatalysts is an effective approach to regulate the adsorption energy of intermediates, alter reaction pathways, lower the energy barrier of the rate-determining step, and ultimately improve electrocatalytic water splitting performance. In this review, a comprehensive overview of the recent advancements in modulating the d-band center for enhanced electrocatalytic water splitting is offered. Initially, the basics of the d-band theory are discussed. Subsequently, recent modulation strategies that aim to boost electrocatalytic activity, with particular emphasis on the d-band center as a key indicator in water splitting are summarized. Lastly, the importance of regulating electrocatalytic activity through d-band center, along with the challenges and prospects for improving electrocatalytic water splitting performance by fine-tuning the transition metal d-band center, are provided.

Impact of graphene incorporation on the oxygen evolution reaction of Co-Fe-based electrocatalysts synthesized via one-step electrodeposition

The oxygen evolution reaction (OER) presents a major challenge for water splitting due to its slow kinetics. In this study, Co-Fe-Gr nanocomposite coatings were developed on carbon steel via electrodeposition using graphene (Gr) at concentrations of 0.02, 0.04, and 0.06 g/L to enhance OER performance. The sample with 0.02 g/L Gr exhibited a unique cauliflower-like morphology with aligned cobalt, as revealed by FE-SEM, leading to an increased electrochemical surface area. This optimal nanocomposite (Co-Fe-Gr (0.02 g/L)) demonstrated a low overpotential of 88 mV at 10 mA cm2, high stability (4.2 mF cm⁻2), and low resistance (R = 7.5 Ω cm⁻2). Additionally, it showed a small Tafel slope of 6.6 mV/dec and maintained stability after 12 h. A turnover frequency (TOF) of 73.6 s⁻1 indicated that graphene doping significantly reduced the adsorption energy of intermediates, greatly enhancing OER activity for efficient water splitting applications.

Phosphor-doping modulates the d-band center of Fe atoms in Fe-N4 catalytic sites to boost the activity of oxygen reduction

Regulating the electronic structure by phosphor-doping is a preferred strategy to boost the performance of carbon-based catalysts for oxygen reduction reaction (ORR). Here, a porous Fe, P, N-codoped carbon catalyst (PCF-FeTz-900) is designed by a phytic acid-assisted thermal etching strategy, in which P atoms are first doped into the carbon matrix to form a stable PC bond, and then FeN4 sites are produced from Fe-2,4,6-Tris(2-pyridyl)-s-triazine complex (Fe-TPTz). Theoretical calculations suggest that the electrons are transferred from the doped P atom to the neighboring FeN4 sites, which facilitates the ORR at the Fe sites by reducing the energy barrier and the adsorption energy of intermediates. Additionally, the P-doped FeN4 (FeN4P) structure manifests a lower free energy difference than that of FeN4 and the d-band center of Fe is also lowered, which further ensures its higher ORR catalytic ability. As a result, the PCF-FeTz-900 catalyst exhibits superior ORR activity and stability in alkaline electrolyte, and the assembled primary zinc-air battery shows greater performances compared to the commercial Pt/C catalyst. This work can provide an effective pathway for modulating the performance of doped-carbon materials in energy conversion devices.

Oxygen vacancy-engineered cerium oxide mediated by copper-platinum exhibit enhanced SOD/CAT-mimicking activities to regulate the microenvironment for osteoarthritis therapy

Cerium oxide (CeO2) nanospheres have limited enzymatic activity that hinders further application in catalytic therapy, but they have an “oxidation switch” to enhance their catalytic activity by increasing oxygen vacancies. In this study, according to the defect-engineering strategy, we developed PtCuOX/CeO2-X nanozymes as highly efficient SOD/CAT mimics by introducing bimetallic copper (Cu) and platinum (Pt) into CeO2 nanospheres to enhance the oxygen vacancies, in an attempt to combine near-infrared (NIR) irradiation to regulate microenvironment for osteoarthritis (OA) therapy. As expected, the Cu and Pt increased the Ce3+/Ce4+ ratio of CeO2 to significantly enhance the oxygen vacancies, and simultaneously CeO2 (111) facilitated the uniform dispersion of Cu and Pt. The strong metal-carrier interaction synergy endowed the PtCuOX/CeO2-X nanozymes with highly efficient SOD/CAT-like activity by the decreased formation energy of oxygen vacancy, promoted electron transfer, the increased adsorption energy of intermediates, and the decreased reaction activation energy. Besides, the nanozymes have excellent photothermal conversion efficiency (55.41%). Further, the PtCuOX/CeO2-X antioxidant system effectively scavenged intracellular ROS and RNS, protected mitochondrial function, and inhibited the inflammatory factors, thus reducing chondrocyte apoptosis. In vivo, experiments demonstrated the biosafety of PtCuOX/CeO2-X and its potent effect on OA suppression. In particular, NIR radiation further enhanced the effects. Mechanistically, PtCuOX/CeO2-X nanozymes reduced ras-related C3 botulinum toxin substrate 1 (Rac-1) and p-p65 protein expression, as well as ROS levels to remodel the inflammatory microenvironment by inhibiting the ROS/Rac-1/nuclear factor kappa-B (NF-κB) signaling pathway. This study introduces new clinical concepts and perspectives that can be applied to inflammatory diseases.Graphical

Exploring the catalytic characteristics of binuclear bimetallic FeM sites (M = Co, Ni, Pt) on nitrogen-doped graphene through density functional theory and ab initio molecular dynamics

Certain supported bimetallic catalysts exhibit high efficiency in both oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). However, the catalytic mechanism of double-atom catalysts and how different-atom active sites affect charge transfer efficiency have not been fully revealed. In this work, we provide density functional theory (DFT) simulations of ORR/OER on FeM-NC (M = Co, Ni, Pt) supported on nitrogen-doped graphene. The stability of structures, electrical properties, adsorption energies of intermediates, and catalytic activity of ORR/OER on FeM-NC have been investigated. The results indicate that the Fe-atom in stable FeM-NC structures is a catalytically active site and that the FeM-NC-1 structures may be more appropriate as catalysts. The overpotentials for ORR/OER on FeM-NC-1 (M = Co, Ni, Pt) are 0.42/0.29 V on FeCo-NC-1, 0.57/0.33 V on FeNi-NC-1, and 0.64/0.33 V on FePt-NC-1, which is significantly lower than those on Pt(111) surfaces. Ab initio molecular dynamics (AIMD) simulations suggest that ORR/OER may occur vis a typical four-electron mechanism on FeNi-NC-1 and FePt-NC-1 configurations, while on FeCo-NC-1 structures, it may involve two different four-electron pathways. This study increases our knowledge of the structural stability of FeM-NC-1 structures as bifunctional catalysts and the ORR/OER pathway in acidic solution, and it also shows that three FeM-NC-1 structures are suitable candidate catalysts for ORR/OER.

Breaking through the State-of-the-Art Frontier in Oxygen Electrocatalysis: Geometry Adaptive Catalysts (GACs)

The grand challenge in oxygen electrocatalysis lies in overcoming scaling relations. The theoretical activity volcano positions the ideal catalyst at the apex. However, the OH–OOH scaling relation determines a linear path on the volcano surface that limits the activity. The current state-of-the-art (SOTA) in modeling confirms this scaling relation, at the same time it hinders the experimental development of novel oxygen reduction reaction (ORR) catalysts, impeding progress in sustainable energy solutions. To address this challenge, we propose to use the geometry effect and introduce the concept of Geometry Adaptive Catalysts (GACs).[1]The geometry effect, based on preliminary research, involves changing catalytic activity by adjusting the adsorption energy of intermediates through the control of catalyst geometry. Our goal is to break through the SOTA frontier for ORR by synthesizing GACs and supporting our efforts with theoretical and computational modeling of the geometric effect. In this work we aimed to utilize the geometry effect by synthesizing GACs with various controlled structures, including specific intersite distances, and variable curvature. This enables precise control of catalyst geometry, allowing manipulation of catalytic activity and overcoming scaling relations. Key geometric parameters, namely inter-site distance, curvature, and specific stabilizations of ORR intermediates, are explored to test our hypothesis: Controlling catalyst geometry adjusts the ORR mechanism and adsorption energies of intermediates, enabling the switching, pushing, and even bypassing of scaling relations.This approach holds promise for substantial improvements in environmental sustainability and human life quality, with broad applicability to various electrocatalytic reactions beyond ORR.

(Invited) Nitrogen-Doped High-Entropy Alloy as Efficient and Stable Electrocatalyst

The development of Pt-based catalysts for use in fuel cells that meet performance targets of high activity, maximized stability, and low cost remains a huge challenge. The high-entropy alloy (HEA) is one of the most promising candidates for electrocatalysts, owing to their unique properties involving the high entropy effect, lattice distortion effect, sluggish diffusion effect, and “cocktail” effect.1 Alternatively, nitrogen (N)-doping effects have been well documented and demonstrated in our previous studies, which further fine-tune the adsorption energetics of intermediates and improve the corrosion resistance by the pinning effect of metal-nitrogen bonds.2-3 Combining the HEA and N-doping strategies, the tailored lattice and interstice atomic sites lead to the formation of chemically stable multiple metal-nitrogen (M-N) bonds and the generation of the possible synergistic effect on promoting ORR performance. Herein, we report a N-doped high-entropy alloy (HEA) electrocatalyst that consists of a Pt-rich shell and a N-doped PtCoFeNiCu core on a carbon support (denoted as N-Pt/HEA/C). The N-Pt/HEA/C catalyst showed high mass activity of 1.34 A mgPt -1 at 0.9 V for the oxygen reduction reaction (ORR), which substantially outperformed commercial Pt/C and most of the other binary/ternary Pt-based catalysts. The N-Pt/HEA/C catalyst also demonstrated excellent stability in both rotating disk electrode (RDE) and membrane electrode assembly (MEA) testing. Using operando X-ray absorption spectroscopy (XAS) measurements and theoretical calculations, we revealed that the enhanced ORR activity of N-Pt/HEA/C originated from the optimized adsorption energy of intermediates, consequent of the tailored electronic structure formed upon the N-doping. Furthermore, we showed that the multiple metal-nitrogen bonds formed synergistically improved the corrosion resistance of the 3d transition metals and enhanced the ORR durability.References Yao, Y.; Dong, Q.; Brozena, A.; Luo, J.; Miao, J.; Chi, M.; Wang, C.; Kevrekidis, I. G.; Ren, Z. J.; Greeley, J.; Wang, G.; Anapolsky, A.; Hu, L., High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery. Science 2022, 376 (6589), eabn3103.Zhao, X.; Xi, C.; Zhang, R.; Song, L.; Wang, C.; Spendelow, J. S.; Frenkel, A. I.; Yang, J.; Xin, H. L.; Sasaki, K., High-Performance Nitrogen-Doped Intermetallic PtNi Catalyst for the Oxygen Reduction Reaction. ACS Catalysis 2020, 10 (18), 10637-10645.Zhao, X.; Cheng, H.; Song, L.; Han, L.; Zhang, R.; Kwon, G.; Ma, L.; Ehrlich, S. N.; Frenkel, A. I.; Yang, J.; Sasaki, K.; Xin, H. L., Rhombohedral Ordered Intermetallic Nanocatalyst Boosts the Oxygen Reduction Reaction. ACS Catalysis 2020, 11 (1), 184-192.

Atomically Dispersed Iridium on Polyimide Support for Acidic Oxygen Evolution.

Designing a high-performing iridium (Ir) single-atom catalyst is desired for acidic water electrolysis, which shows enormous potential given its high catalytic activity toward acidic oxygen evolution reaction (OER) with minimum usage of precious Ir metal. However, it still remains a substantial challenge to stabilize the Ir single atoms during the OER operation without sacrificing the activity. Here, we report a high-performing OER catalyst by immobilizing Ir single atoms on a polyimide support, which exhibits a high mass activity on a carbon paper electrode while simultaneously achieving outstanding stability with negligible decay for 360 h. The resulting electrode (denoted as Ir1-PI@CP) reaches a 49.7-fold improvement in mass activity compared to the counterpart electrode prepared without polyimide support. Both our experimental and theoretical results suggest that, owing to the strong metal-support interactions, the polyimide support can enhance the Ir 5d states of Ir single atoms in Ir1-PI@CP, which can tailor the adsorption energies of intermediates and decrease the thermodynamic barrier at the rate-determining step of the OER, but also facilitate the proton-electron-transfer process and improve the reaction kinetics. This work offers an alternative avenue for developing single-atom catalysts with superior activity and durability toward various catalytic systems and beyond.

Co–FeOOH thin nanosheets derived from 2D ZIF-L for efficient oxygen evolution reaction

The complicated reaction pathway and slow electron-transfer kinetics of the oxygen evolution reaction (OER) have been identified as a critical bottleneck that restricts the overall performance of electrochemical water splitting. Metal oxyhydroxides have emerged as viable alternative catalysts as compared to the precious metal-based commercial benchmarks. Yet, the activity may be compromised by the instability of the layered structures. Herein, a simple two-step method is developed for the synthesis of Co–FeOOH electrocatalysts by thermal treatment of cobalt-containing zeolitic imidazolate framework (ZIF-L) deposited on the skeleton of NF (nickel foam) in the presence of FeSO4 and urea. Co–FeOOH/NF, the thin nanosheet arrays exhibit a high specific surface area and high hydrophobicity. The addition of Co regulates the electronic environment around the Fe center, which optimizes the adsorption energy of intermediates and enhances the inherent OER activity of active sites. The Co–FeOOH nanoarrays show excellent OER performance and 99.7% Faradaic efficiency (FE). At current densities of 10 and 100 mA cm−2, there is a low overpotential of 208 and 249 mV, respectively at 1 M KOH. This kind of synthesis method will provide a promising approach for the construction of catalysts featuring stable structures for alkaline water oxidation.

Theoretical study of the effects of surface Cu coordination environment on CO2 hydrogenation to CH3OH

The coordination environment of Cu (the coordination number and arrangement of surface atoms) plays an important role in CO2 hydrogenation to CH3OH. Compared with the extensive studies of the effects of coordination number, the comprehensive effects of coordination number and arrangement of surface atoms were seldom explored in literature. To unravel the effects of surface Cu coordination environment on CO2 hydrogenation to CH3OH, the adsorption and reaction behaviors of H2 and CO2 on Cu(111), (100), (110) and (211) with different coordination numbers and arrangement of surface Cu were systematically calculated by density functional theory (DFT) and kinetic Monte Carlo (kMC) simulation. It was found that the adsorption energies of intermediates in CO2 hydrogenation on Cu surfaces increase with the decrease of coordination number. When the Cu coordination numbers are similar, the charge density on the open surface derived from the different atom arrangement becomes larger and leads to stronger interaction with intermediates than that on the compact one. DFT calculation and kMC simulation indicate that methanol formation pathway follows CO2*→HCOO*→HCOOH*→H2COOH*→H2CO*→CH3O*→CH3OH* on four Cu facets; CO formation is via CO2 direct dissociation on Cu(111), (100) and (110) but COOH* dissociation on (211). The low-coordinated surface Cu with more openness on Cu(211) is the highly active site for CO2 hydrogenation to CH3OH with high turnover of frequency (3.71 × 10−4 s−1) and high selectivity (87.17 %) at 600 K, PCO2 = 7.5 atm and PH2 = 22.5 atm, which is much higher than those on Cu(111), (100) and (110). This work unravels the effects of coordination environment on CO2 hydrogenation at the molecular level and provides an important insight into the design and development of catalysts with high performance in CO2 hydrogenation to CH3OH.

MOFs-derived CoMn-layered double hydroxide array anchored to Ti3C2Tx MXene nanosheets as efficent catalysts for rechargeable lithium-oxygen batteries

Rechargeable lithium-oxygen batteries (LOBs) are acknowledged as potential candidates for advanced energy storage devices as a result of their considerable theoretical energy densities. Nevertheless, they encounter significant challenges throughout discharging and recharging phases, including the difficult decomposition of Li2O2 products, sluggish reaction kinetics, and limited cycle stability. In this study, an efficient catalyst was synthesized by in situ growth of metal–organic frameworks (MOFs)-derived cobalt manganese layered double hydroxide (CoMn-LDH) array on Ti3C2Tx MXene nanosheets (CoMn-LDH@Ti3C2Tx). The LOBs with CoMn-LDH@Ti3C2Tx cathode demonstrated high discharge specific capacity of 27.61 Ah g−1 at 100 mA g−1 and an extended cycle stability of over 224 cycles at 500 mA g−1. Density functional theory (DFT) computations showed that CoMn-LDH@Ti3C2Tx facilitates electron redistribution, optimising the adsorption energy of intermediates, thereby lowering the energy barriers for oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). Consequently, this work presents a multi-level nanostructured catalyst preparation strategy derived from MOFs, offering new insights for the fabrication of efficient electrocatalytic materials.

In-situ electrochemical transformation of F-modified metallic bismuth for highly-efficient CO2 electroreduction and Zn-CO2 battery

Electrocatalytic CO2 reduction (ECO2R) to produce formate is one of the essential routes for CO2 upgrading. Herein, the bismuth oxyfluoride (BiOF) material is firstly rationally designed as a precursor to derive the F-modified Bi catalyst (FD-Bi) for ECO2R. The FD-Bi catalyst achieves more than 90 % Faradaic efficiency of formate (FEformate) over a wide potential range of −0.5 ∼ -1.2 V vs. RHE. By coupling in-situ Raman and infrared spectroscopy, the transformation of BiOF to FD-Bi and the formation of key *OCHO intermediates have been revealed. Density functional theory (DFT) calculations further confirm the optimized electronic structure and the favorable adsorption energies of intermediates on F-modified Bi catalyst. In a coupled system for the co-production of formate, a high FEformate of 159.1 % can be realized at a small cell voltage of 1.9 V. In addition, Zn-CO2 battery equipped with FD-Bi delivers a high power density of 2.68 mW·cm−2 and superior stability.

NiFe layered double hydroxide nanosheets self assembled and etched by phosphotungstic acid for the enhanced oxygen evolution reaction

Poor conductivity and low reaction kinetics of layered double hydroxides (LDHs) hindered their large-scale applications as catalysts in the oxygen evolution reactions (OER). The composites with vacancies, high valence cations and 3D gradient pore structures were synthesized by the ionic exchange, delamination and self-assembly methods. The nanoclusters [PW12O40]3- were successfully intercalated into the interlayers of LDHs due to the static attraction. Meanwhile, the partial metal cations in the layers were etched by its conjugate acid. The molar ratios of Ni:Fe and acid:LDH need to be modulated to achieve the optimum catalytic performances. The composite 1:4PW12–Ni3Fe exhibited a lower overpotential 270 mV at 10 mA cm−2, superior kinetics (43 mV dec−1), better conductivity (2.68 Ω cm−2) and larger turnover frequency (3.59 s−1) than the bulk and nanosheet counterparts with reevesite-like structure. [PW12O40]3- more effectively reduced the overpotentials of LDHs than other interlayer anions (e.g.WO4−, B4O72− and CnH2n+1SO42−). The favourable electrocatalytic performances were attributed to the synergistic effects. The vacancies provided new active centers with high intermediate adsorption energy. The high valances cations induced electronic coupling and spatial charge redistribution. 3D gradient pore structures with a large electrochemical active surface area exposed active sites and provided a convenient path for transferring masses and charges.

Defects engineering of nickel tellurium electrocatalyst to boost urea oxidation reaction: Electrodeposition mechanism and performance

The urea oxidation reaction (UOR) offers an attractive strategy to replace the oxygen evolution reaction (OER) for energy-saving hydrogen production due to its favorable thermodynamic property, but its development is hindered by the lack of efficient and cost-effective electrocatalysts. In this study, nickel-tellurium (Ni-Te) grown on 3D nickel foam was successfully synthesized using a simple and facile electrodeposition method. The electrodeposition process of Ni-Te follows the three-dimensional instantaneous nucleation/growth mechanism controlled by diffusion. The apparent activation energy (Ea) of Ni-Te in the electrodeposition process is as low as 36.5 kJ∙mol-1. Lattice distortion structure obtained by electrodeposition modifies the intrinsic electronic structure and optimizes the adsorption energy of intermediates. Thanks to the synergistic effects of fast electron transport, superhydrophilic surface and nanoflake structure, the prepared Ni-Te electrocatalyst shows excellent activity toward UOR with a low potential of 1.503 V vs. RHE at 100 mA·cm-2 and a small Tafel slope (63.6 mV·dec-1) in 1.0 M KOH containing 0.33 M urea solution.

Elucidating the construction and modulation of built-in electric field in the oxygen evolution reaction

The construction of a built-in electric field (BIEF) is considered to be an effective strategy for enhancing catalyst performance due to its critical role in optimizing adsorption of reactants and key intermediates, as well as its positive impact on interface behavior. Herein, a strategy is developed to elucidate the correlation between oxygen evolution reaction activity and the BIEF and its strength by constructing and enhancing the BIEF through incorporating manganese into Co3O4@NiFe-LDH p-n heterojunction. This Co3O4@NiFe-LDH p-n heterojunction generates a BIEF that effectively regulates electronic structure, facilitates rapid electron transfer, induces alterations in the chemical microenvironment, and modulates intermediate adsorption energy. Notably, when hetoroatomic Mn is incorporated into the p-n heterojunction, particularly encapsulated within NiFe-LDH, a more pronounced enhancement for BIEF is observed. Benefiting from this strong BIEF, Co3O4@Mn/NiFe-LDH exhibits excellent OER activity and stability with an overpotential of only 209 mV at 50 mA cm−2, a Tafel slope of 57 mV dec−1, and stable operation for 110 h at approximately 10 mA cm−2. Moreover, density functional theory (DFT) calculations further confirms that the construction and reinforcement of the BIEF can effectively accelerate the electron transfer rates, adjust the metal d-band center, optimize intermediates adsorption properties, and reduce the reaction energy barriers.

Triple-function Mn regulation of NiFe (oxy)hydroxide for oxygen evolution reaction

Transition metal (oxy)hydroxides are potential oxygen evolution reaction (OER) electrocatalysts; however, simultaneously modulating multiple factors to enhance their performance is a grand challenge. Here, we report an incorporating heteroatom strategy via one-step hydrothermal approach to adjust more than one factor of Mn-doped NiFe (oxy)hydroxide (Mn-NiFeOOH/LDH) heterojunction. Mn doping regulates heterojunction morphology (reducing nanoparticles and becoming thinner and denser nanosheets), Ni/Fe ratio and valence states (Ni2+, Ni3+, and Ni3+Δ) of Ni ions. The former could effectively increase surface active sites, and the latter two reduce the content of Fe in the Mnx-NiFeOOH/LDH heterojunction, enabling more Ni2+ convert to Ni3+/3+Δ that have higher intrinsic OER activity. As a result, the first-rank Mn-NiFeOOH/LDH with ultra-low overpotential of 185 mV@20 mA cm−2 and 296 mV@500 mA cm−2, and the improved OER performance are outdo to those of commercial RuO2 catalyst for OER. Moreover, the Mn-NiFeOOH/LDH affords the earliest initial potential (1.392 V vs. RHE), corresponds to a recorded low overpotential (162 mV). Based on the density functional theory (DFT), Mn dopants can alter intermediate adsorption energy and effectively decrease *OOH’s energy barrier. This research exhibits a feasible strategy to design low cost electrocatalysts and provide new possibilities for future industrialization.

Single-cluster anchored on PC6 monolayer as high-performance electrocatalyst for carbon dioxide reduction reaction: First principles study

Tremendous challenges remain to develop high-efficient catalysts for carbon dioxide reduction reaction (CO2RR) owing to the poor activity and low selectivity. However, the activity of catalyst with single active site is limited by the linear scaling relationship between the adsorption energy of intermediates. Motivated by the idea of multiple activity centers, triple metal clusters (M = Cr, Mn, Fe, Co, Ni, Cu, Pd, and Rh) doped PC6 monolayer (M3@PC6) were constructed in this study to investigate the CO2RR catalytic performance via density functional theory calculations. Results shows Mn3@PC6, Fe3@PC6, and Co3@PC6 exhibit high activity and selectivity for the reduction of CO2 to CH4 with limiting potentials of −0.32, −0.28, and −0.31 V, respectively. Analysis on the high-performance origin shows the more binding sites in M3@PC6 render the triple-atom anchored catalysts (TACs) high ability in regulating the binding strength with intermediates by self-adjusting the charges and conformation, leading to the improved performance of M3@PC6 than dual-atom doped PC6. This work manifests the huge application of PC6 based TACs in CO2RR, which hope to prove valuable guidance for the application of TACs in a broader range of electrochemical reactions.

Aluminum-induced electron structure on nickel phosphide for effective hydrazine‑assisted water splitting at large current density

Hydrazine-assisted water electrolysis emerges as a promising strategy to replace conventional device for effective hydrogen generation. Limited to the great difference of intermediate adsorption energy for hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), the design and fabrication of bifunctional catalysts is still a knotty challenge in industrial conditions. Herein, Al-doped Ni2P nanoflower architecture grown in-situ on nickel foam (Al-Ni2P/NF) is fabricated through the combination of hydrothermal process and subsequent phosphorization treatment. Ascribed to the redistribution of electron state and optimization of reaction intermediate energy induced by Al, Al-Ni2P/NF expresses distinguished bifunctional catalytic performance with ultralow potentials of −205 and 300 mV at 500 mA cm−2 for HER and HzOR, respectively. When integrated into hydrazine-assisted water splitting as both the anode and cathode, only 0.717 V is required to reach a large current density of 500 mA cm−2. Specially, a novel integrated system driven entirely by sustainable solar energy is proposed, generating energy-saving hydrogen and purify hydrazine-containing sewage simultaneously. This work provides an attracting and practical path for accelerating the development of hydrogen economy.

Intercalated PtCo Electrocatalyst of Vanadium Metal Oxide Increases Charge Density to Facilitate Hydrogen Evolution.

Efforts to develop high-performance electrocatalysts for the hydrogen evolution reaction (HER) are of utmost importance in ensuring sustainable hydrogen production. The controllable fabrication of inexpensive, durable, and high-efficient HER catalysts still remains a great challenge. Herein, we introduce a universal strategy aiming to achieve rapid synthesis of highly active hydrogen evolution catalysts using a controllable hydrogen insertion method and solvothermal process. Hydrogen vanadium bronze HxV2O5 was obtained through controlling the ethanol reaction rate in the oxidization process of hydrogen peroxide. Subsequently, the intermetallic PtCoVO supported on two-dimensional graphitic carbon nitride (g-C3N4) nanosheets was prepared by a solvothermal method at the oil/water interface. In terms of HER performance, PtCoVO/g-C3N4 demonstrates superior characteristics compared to PtCo/g-C3N4 and PtCoV/g-C3N4. This superiority can be attributed to the notable influence of oxygen vacancies in HxV2O5 on the electrical properties of the catalyst. By adjusting the relative proportions of metal atoms in the PtCoVO/g-C3N4 nanomaterials, the PtCoVO/g-C3N4 nanocomposites show significant HER overpotential of η10 = 92 mV, a Tafel slope of 65.21 mV dec-1, and outstanding stability (a continuous test lasting 48 h). The nanoarchitecture of a g-C3N4-supported PtCoVO nanoalloy catalyst exhibits exceptional resistance to nanoparticle migration and corrosion, owing to the strong interaction between the metal nanoparticles and the g-C3N4 support. Pt, Co, and V simultaneous doping has been shown by Density Functional Theory (DFT) calculations to enhance the density of states (DOS) at the Fermi level. This augmentation leads to a higher charge density and a reduction in the adsorption energy of intermediates.

Superstructure-Assisted Single-Atom Catalysis on Tungsten Carbides for Bifunctional Oxygen Reactions.

Single-atom catalysis (SAC) attracts wide interest for zinc-air batteries that require high-performance bifunctional electrocatalysts for oxygen reactions. However, catalyst design is still highly challenging because of the insufficient driving force for promoting multiple-electron transfer kinetics. Herein, we report a superstructure-assisted SAC on tungsten carbides for oxygen evolution and reduction reactions. In addition to the usual single atomic sites, strikingly, we reveal the presence of highly ordered Co superstructures in the interfacial region with tungsten carbides that induce internal strain and promote bifunctional catalysis. Theoretical calculations show that the combined effects from superstructures and single atoms strongly reduce the adsorption energy of intermediates and overpotential of both oxygen reactions. The catalyst therefore presented impressive bifunctional activity with an ultralow potential gap of 0.623 V and delivered a high power density of 188.5 mW cm-2 for assembled zinc-air batteries. This work opens up new opportunities for atomic catalysis.