Proton Adsorption Research Articles

Mott–Schottky heterostructure induce the interfacial electron redistribution of MoS2 for boosting pH-universal hydrogen evolution with Pt-like activity

MoS2 have been regarded as promising catalysts for the hydrogen evolution reaction (HER). However, its poor catalytic performance in neutral and alkaline solution would be problematic for the practical application. Combining semiconductors with metals as Mott-Schottky heterojunctions (MSH) has been regarded as an effective way to improve catalytic activity. Herein, a pH-universal adaptability Mo-MoS2 MSH has been constructed via an in-situ lithiation method. The constructed MSH structure can effectively optimize the sulfur sites’ electronic structure with interfacial electron redistribution and enhance the proton adsorption property under all pH conditions. To achieve the current density of 10 mA cm−2, it only needs overpotentials of 91, 138 and 128 mV in 0.5 M H2SO4, 1.0 M KOH and 1.0 M PBS, respectively, which has been one of the best values of current noble-metal-free electrocatalyst. This work can pave a valuable approach for the design high activity HER electrocatalysts for pH-universal with Pt-like activity.

Superlative photoelectrochemical properties of 3D MgCr-LDH nanoparticles influencing towards photoinduced water splitting reactions

In the present work, we report the synthesis of single system three-dimensional (3D) open porous structure of MgCr-LDH nanoparticles in a substrate-free path by using one-step formamide assisted hydrothermal reaction followed by visible light irradiation for significant photoelectrochemical (PEC) properties that manifest towards photocatalytic H2 and O2 production. The as-prepared nanostructured materials were characterized by various physico-chemical characterization techniques. Moreover, this unique synthetic approach produces 3D open porous network structure of MgCr-LDH nanoparticles, which were formed by stacking of numerous 2D nanosheets, for effective light harvestation, easy electronic channelization and unveil superlative PEC properties, including high current density (6.9 mA/cm2), small Tafel slope of 82 mV/decade, smallest arc of the Nyquist plot (59.1 Ω cm−2) and photostability of 6000 s for boosting water splitting activity. In addition, such perfectly self-stacked 2D nanosheets in 3D MgCr-LDH possess more surface active defect sites as enriched 50% oxygen vacancy resulting a good contact surface within the structure for effective light absorption along with easy electron and hole separation, which facilitates the adsorption of protons and intermediate for water oxidation. Additionally, the Cr3+ as dopant pull up the electrons from water oxidation intermediates, thereby displaying superior photocatalytic H2 and O2 production activity of 1315 μmol/h and 579 μmol/h, respectively. Therefore, the open 3D morphological aspects of MgCr-LDH nanoparticles with porous network structure and high surface area possess more surface defect sites for electron channelization and identified as distinct novel features of this kind of materials for triggering significant PEC properties, along with robustly enhance the photocatalytic water splitting performances.

Hydrogen evolution reaction on Pt and Ru in alkali with volmer-step promotors and electronic structure modulators

Alkaline water electrolysis despite having a variety of choices for anodic oxygen evolution reaction (OER) catalysts out of non-precious metals suffers significantly due to the poor kinetics of cathodic hydrogen evolution reaction (HER) even with the state-of-the-art Pt and equally active Ru. The Volmer-step (water dissociation (WD) coupled proton adsorption) of alkaline HER is mostly the rate-determining step (RDS) and costs most of the work required. In this review, recent developments in improving the HER kinetics of Pt and Ru with Volmer-step promotors and electronic structure modulators have been comprehensively analyzed and critically presented with the challenges and prospects.

Engineering FeP4/CoFe2O4 heterostructure with balanced proton adsorption ability for efficient hydrogen evolution reaction

Developing cost-efficient electrocatalysts for hydrogen evolution reaction (HER) with low overpotential, fast kinetics and good stability is one of the challenges to promote the industrial application of water electrolysis technology. Herein, we construct a novel heterostructure electrocatalyst with abundant FeP4 nanoparticles grown on the surface of CoFe2O4 nanosheets for efficient HER catalysis. FeP4, as the crucial co-catalyst, not only promotes the proton adsorption process due to its large electronegativity but also improves the electron structure around the Co sites for optimizing H* coupling and H2 evolution process. Consequently, the FeP4/CoFe2O4 heterostructure electrocatalyst shows a much improved HER performance (η100 = 168 mV) and a faster reaction kinetics by comparing with the pristine FeP4 and CoFe2O4. Further electrochemical characterization demonstrates that the heterostructure is also beneficial to increase active sites and enhance intrinsic activity. This work provides a feasible perspective for constructing heterostructure to acquire excellent HER catalysts.

Spin-related bimetallic-hybridization induced by asymmetric super-nearest exchange interaction in single-atom dimer for hydrogen evolution reaction

Hydrogen evolution reaction (HER) plays a critical role in designing energy conversion devices, but is facing the challenges of low-cost electrocatalysts and insufficient understanding about spin-related reaction kinetics. Different from traditional nanostructures, this work focuses on the spin-related orbital hybridization and charger transfer by bimetallic super-nearest exchange interaction to improve the catalytic activity of single-atom dimer (SAD). Herein, systematic first-principle screening discloses that the spin-related electronic reconfiguration at the SAD atomic interface can optimize the occupied sates at 3d-orbtial and shift the d-band center, thereby, benefiting for proton adsorption and dissociation. As a result, the Gibbs free energy and carrier transfer can be effectively optimized. Our findings provide a new insight into steering spin-related orbital interaction and designing new-type catalyst.

Patchwork-Structured Heterointerface of 1T-WS2/a-WO3 with Sustained Hydrogen Spillover as a Highly Efficient Hydrogen Evolution Reaction Electrocatalyst.

Using tungsten disulfide (WS2) as a hydrogen evolution reaction (HER) electrocatalyst brought on several ways to surpass its intrinsic catalytic activity. This study introduces a nanodomain tungsten oxide (WO3) interface to 1T-WS2, opening a new route for facilitating the transfer of a proton to active sites, thereby enhancing the HER performance. After H2S plasma sulfurization on the W layer to realize nanocrystalline 1T-WS2, subsequent O2 plasma treatment led to the formation of amorphous WO3 (a-WO3), resulting in a patchwork-structured heterointerface of 1T-WS2/a-WO3 (WSO). Addition of a hydrophilic interface (WO3) facilitates the hydrogen spillover effect, which represents the transfer of absorbed protons from a-WO3 to 1T-WS2. Moreover, the faster response of the cathodic current peak (proton insertion) in cyclic voltammetry is confirmed by the higher degree of oxidation. The rationale behind the faster proton insertion is that the introduced a-WO3 works as a proton channel. As a result, WSO-1.2 (the ratio of 1T-WS2 to a-WO3) exhibits a remarkable HER activity in that 1T-WS2 consumes more protons provided by the channel, showing an overpotential of 212 mV at 10 mA/cm2. Density functional theory calculations also show that the WO3 phase gives higher binding energies for initial proton adsorption, while the 1T-WS2 phase shows reduced HER overpotential. This improved catalytic performance demonstrates a novel strategy for water splitting to actively elicit the related reaction via efficient proton transport.

Norbornane derived N-doped sp2 carbon framework as an efficient electrocatalyst for oxygen reduction reaction and hydrogen evolution reaction

Hitherto, the development of Pt free bifunctional electrocatalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is necessary for the advancement of sustainable and cost-effective solutions for energy conversion and storage technology. In this direction, herein we elucidated the usage of N doped sp2 hybridized carbon framework (N-CF) as a metal-free electrocatalyst for ORR and HER. This work inspects the effect of N doping that converts a hybrid structure of CF {Norbornane or bicyclo [2,2,1] heptane structure} into planar N-CF. A series of N-doped CF with different doping concentrations has been prepared using a facile and cost-effective technique. This robust electrocatalysts exhibits a promotional effect in the activity, porosity, thermal and electrochemical stability for the ORR and HER reactions. A rich delocalized electronic density of the sp2 bounded N species helps in modulating antibonding state of molecular oxygen and facilitates the breakage of OO bond in ORR. It also promotes proton adsorption via bonding between proton and valence electron rich catalyst surface to aid HER. The research sought to investigate the employability of N-CF for fabricating sustainable energy devices with electrocatalyst possessing multiple electrocatalytic activities for ORR and HER. Density Functional Theory (DFT) computations reveals that active sites for HER are carbon atom located at the edge close to pyrrolic nitrogen and adjacent to graphitic nitrogen dopants.

Influence of stoichiometry on the corrosion response of titanium oxide coatings produced by plasma electrolytic oxidation

In this study the corrosion mechanism leading to coating debonding in acidic environments, produced by plasma electrolytic oxidation (PEO) on Ti, is investigated through electrochemical impedance spectroscopy (EIS), potential step chronometric, and a detailed structural characterization according to the use of electron energy loss spectroscopy (EELS). It will be demonstrated that a slightly reduced oxide will enhance proton adsorption and percolation leading to oxide debonding, while the synthesis of a barrier layer mainly composed by Ti 4 + oxide bearing phases and low sulfur content will retard H + permeation enhancing H2 evolution in correspondence of the oxide surface.

Modulating Pt-O-Pt atomic clusters with isolated cobalt atoms for enhanced hydrogen evolution catalysis

Platinum is the most efficient catalyst for hydrogen evolution reaction in acidic conditions, but its widespread use has been impeded by scarcity and high cost. Herein, Pt atomic clusters (Pt ACs) containing Pt-O-Pt units were prepared using Co/N co-doped carbon (CoNC) as support. Pt ACs are anchored to single Co atoms on CoNC by forming strong interactions. Pt-ACs/CoNC exhibits only 24 mV overpotential at 10 mA cm−2 and a high mass activity of 28.6 A mg−1 at 50 mV, which is more than 6 times higher than commercial Pt/C with any Pt loadings. Spectroscopic measurements and computational modeling reveal the enhanced hydrogen generation activity attributes to the charge redistribution between Pt and O atoms in Pt-O-Pt units, making Pt atoms the main active sites and O linkers the assistants, thus optimizing the proton adsorption and hydrogen desorption. This work opens an avenue to fabricate noble-metal-based ACs stabilized by single-atom catalysts with desired properties for electrocatalysis.

A crucial role of enhanced Volmer-Tafel mechanism in improving the electrocatalytic activity via synergetic optimization of host, interlayer, and surface features of 2D nanosheets

High-performance electrocatalysts have attracted growing interest because of their crucial roles in renewable energy technologies. In this study, the host, interlayer, and surface features of electrocatalytically-active 2D nanosheets (NSs) are systematically controlled with the synergetic combination of host−guest co-engineering and surface modification to develop a novel synthetic strategy for efficient electrocatalysts. Molecular-level control of interfacial electronic coupling and surface reactivity can be achieved by the self-assembly of MoS2/RuO2 NS mixtures with variable-sized tetraalkylammonium cations and subsequent thermal aging. The resulting optimization of the operation mechanisms of restacked MoS2/RuO2 NSs effectively improves the electrocatalyst functionality for hydrogen evolution reaction (HER). The extensive modifications of diverse structural and morphological parameters allow the elucidation of a linear correlation between electrochemical active surface area and HER overpotential. Systematic in-situ spectroscopic analyses clearly demonstrate the crucial role of enhanced Volmer−Tafel mechanism in improving the electrocatalytic activity via enhancement of proton adsorption and interfacial electron transfer.

Spectroscopic characterization of biosynthesized lead oxide (PbO) nanoparticles and their applications in PVC/graphite-PbO nanocomposites

Abstract Extract of Hibiscus rosa-sinensis plants was used for the green synthesis of PbO nanoparticles. The prepared nanoparticles were conformed with the help of SEM, X-ray diffraction, FTIR and UV-visible spectroscopy. The prepared PbO nanoparticles were dispersed in deionized water and mixed with graphite to get graphite-PbO (G-PbO) filler. Seven different nanocomposite membranes with variable compositions (5, 10, 15, 20, 25, 30 and 35%) of PVC/G-PbO were prepared in tetrahydrofuran (THF) solvent using solution casting method. Different physiochemical parameters of the nanocomposite membranes studied included morphology, porosity, density, water uptake, swelling degree, electrical conductivity and proton adsorption capacity. All these physiochemical parameters were compared with pure PVC membranes available in literature. It was found that the addition of G-PbO filler in PVC polymer improved all the physiochemical properties except density. PVC/G-PbO membranes showed 42.65 times more electrical conductivity and 5.90 times more ion adsorption capacities compare to pure PVC membranes.

Hydrogen spillover in complex oxide multifunctional sites improves acidic hydrogen evolution electrocatalysis

Improving the catalytic efficiency of platinum for the hydrogen evolution reaction is valuable for water splitting technologies. Hydrogen spillover has emerged as a new strategy in designing binary-component Pt/support electrocatalysts. However, such binary catalysts often suffer from a long reaction pathway, undesirable interfacial barrier, and complicated synthetic processes. Here we report a single-phase complex oxide La2Sr2PtO7+δ as a high-performance hydrogen evolution electrocatalyst in acidic media utilizing an atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from comprehensive experiments and theoretical calculations, the overall hydrogen evolution pathway proceeds along three steps: fast proton adsorption on O site, facile hydrogen migration from O site to Pt site via thermoneutral La-Pt bridge site serving as the mediator, and favorable H2 desorption on Pt site. Benefiting from this catalytic process, the resulting La2Sr2PtO7+δ exhibits a low overpotential of 13 mV at 10 mA cm−2, a small Tafel slope of 22 mV dec−1, an enhanced intrinsic activity, and a greater durability than commercial Pt black catalyst.

Controlled Formation of Dimers and Spatially Isolated Atoms in Bimetallic Au-Ru Catalysts via Carbon-Host Functionalization.

The introduction of a foreign metal atom in the coordination environment of single-atom catalysts constitutes an exciting frontier of active-site engineering, generating bimetallic low-nuclearity catalysts often exhibiting unique catalytic synergies. To date, the exploration of their full scope is thwarted by (i) the lack of synthetic techniques with control over intermetallic coordination, and (ii) the challenging characterization of these materials. Herein, carbon-host functionalization is presented as a strategy to selectively generate Au-Ru dimers and isolated sites by simple incipient wetness impregnation, as corroborated by careful X-ray absorption spectroscopy analysis. The distinct catalytic fingerprints are unveiled via the hydrogen evolution reaction, employed as a probe for proton adsorption properties. Intriguingly, the virtually inactive Au atoms enhance the reaction kinetics of their Ru counterparts already when spatially isolated, by shifting the proton adsorption free energy closer to neutrality. Remarkably, the effect is magnified by a factor of 2 in dimers. These results exemplify the relevance of controlling intermetallic coordination for the rational design of bimetallic low-nuclearity catalysts.

Computation-guided design and preparation of durable and efficient WC-Mo2C heterojunction for hydrogen evolution reaction

Molybdenum and tungsten carbides (Mo 2 C and WC) are promising catalysts for hydrogen evolution reaction (HER), but their electrocatalytic activities are still inferior to theoretical predictions. Herein, density functional theory (DFT) calculations imply that WC-Mo 2 C heterostructure may exert a high HER performance since the hybridization of WC and Mo 2 C can optimize the proton adsorption energy and energy barrier for water dissociation. To test this predication, we prepare the WC-Mo 2 C heterostructure on a flexible carbon cloth (CC). The obtained WC-Mo 2 C@CC exhibits notable HER activity ( η10 = 122 mV; η500 = 309 mV) and stability (continuous 100 h at 500 mA cm −2 ) in alkaline media. Furthermore, a solar-panel-driven electrolyzer, including the WC-Mo 2 C@CC cathode and a NiFe-LDH@Ni f anode, operates at 10 mA cm −2 with a cell voltage of 1.51 V in 10 M KOH at 70°C, demonstrating its potential for practical applications. Overall, this work offers an atomic-level insight into designing advanced carbide HER electrocatalysts. • WC-Mo 2 C heterostructures are prepared by one-step co-deposition • WC-Mo 2 C show competitive alkaline catalytic HER performance • The optimized ΔG H∗ and super hydrophilic nature account for its good HER activity • A water electrolyzer driven by solar energy is operated at industrial conditions WC-Mo 2 C heterostructures are prepared by one-step co-deposition in KF-B 2 O 3 -Na 2 WO 4 -Na 2 MoO 4 molten salts by Liu et al. The WC-Mo 2 C heterostructures show a high HER performance owing to the optimized ΔG H∗ and low energy barrier for water spitting.

Low proton adsorption energy barrier of S-scheme p-CNQDs/VO-ZnO for thermodynamics and kinetics favorable hydrogen evolution

Traditional photocatalytic hydrogen evolution path with high energy barrier of proton adsorption limits the reaction efficiency. Specific regulation on active site to realize low energy barrier hydrogen generation provides a new perspective. In this work, an innovative low barrier route is provided on protonated N of g-C3N4 of S-scheme protonated g-C3N4 quantum dots/ZnO hybrid rich in oxygen vacancies (p-CNQDs/VO-ZnO). VO generated by quantum dots doping optimizes the electron structure of S-scheme, whereas the intensive electron directional transmission in S-scheme promotes protonation of p-CNQDs. Profited from the synergies of thermodynamic and dynamic, protons and electrons concentrate at edge-active N accomplish the efficient photocatalytic HER with a 117-fold elevated H2 evolution. This work provides more possibilities for designing low energy pathway and efficient catalyst in H2 evolution reaction.

Regulating the Electronic Configuration of Supported Iron Nanoparticles for Electrochemical Catalytic Nitrogen Fixation

AbstractElectrocatalytic nitrogen reduction reaction (eNRR) is a sustainable alternative to the traditional Haber–Bosch process due to its eco‐friendly nature and capability of utilizing renewable energy. However, its low Faradic efficiency (FE), caused by the excessive adsorption and reduction of protons, has been regarded as the main challenge, which leads to low ammonia yield as well. Herein, a carbon‐supported iron electrocatalyst is reported, which is fabricated by low‐temperature (300 °C) potassium vapor reduction of FeF3‐intercalated graphite fluoride, for efficient electrochemical nitrogen reduction. The strategy enables the unique formation of exposed Fe nanoparticles uniformly anchored on graphene and in situ doped with fluorine heteroatoms. These specific features can alter the electronic configuration of the Fe nanoparticles, leading to strong surface polarization that boosts nitrogen absorption capability for eNRR, resulting in high FE (41.6%) and ammonia yield rate (53.3 μg h‐1 mg‐1) simultaneously. First‐principle calculation attributes this enhanced eNRR capability to more empty orbitals carried by the Fe atoms through the electron transfer with F dopant and substrate. As a versatile strategy for synthesizing various ultrafine and highly dispersed metal nanoparticles on the carbon support, this work might shed light on rational designing essential electrocatalysts with effective electronic structure manipulation.

Activating MoS2 via electronic structure modulation and phase engineering for hydrogen evolution reaction

The local electronic configuration of active sites in molybdenum disulfide (MoS2) could significantly alter the intrinsic activity towards hydrogen evolution reaction (HER). Herein, we report that the HER performance of MoS2 electrocatalysts was boosted via bismuth and palladium co-doping. The introduction of heteroatom Bi successfully altered the local electronic configuration of S atoms in the MoS2 inert basal plane to form an electron-enriched environment, conducive to boost active site density and proton adsorption, as experimentally verified by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Furthermore, after activating the MoS2 via Pd doping, a phase transition to stable 1 T phase occurred which was verified by Raman. In acidic media, the as-prepared Bi/Pd-MoS2 catalyst exhibited excellent electrochemical HER performance in terms of a low overpotential of -114 mV at a current density of 10 mA cm−2, a small Tafel slope of 65 mV dec−1, and outstanding long-term stability.

Highly selective cesium(I) capture under acidic conditions by a layered sulfide

Radiocesium remediation is desirable for ecological protection, human health and sustainable development of nuclear energy. Effective capture of Cs+ from acidic solutions is still challenging, mainly due to the low stability of the adsorbing materials and the competitive adsorption of protons. Herein, the rapid and highly selective capture of Cs+ from strongly acidic solutions is achieved by a robust K+-directed layered metal sulfide KInSnS4 (InSnS-1) that exhibits excellent acid and radiation resistance. InSnS-1 possesses high adsorption capacity for Cs+ and can serve as the stationary phase in ion exchange columns to effectively remove Cs+ from neutral and acidic solutions. The adsorption of Cs+ and H3O+ is monitored by single-crystal structure analysis, and thus the underlying mechanism of selective Cs+ capture from acidic solutions is elucidated at the molecular level.

New insights into interface charge-transfer mechanism of copper-iron layered double hydroxide cathodic electrocatalyst in alkaline electrolysis

Transition metal layered hydroxides are potential catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction in alkaline electrolysis (AE). Recent researches focused on NiFe layered double hydroxide (LDH) as efficient, cost-effective electrocatalyst due to the proton and hydroxide adsorption kinetics by Ni and Fe. However, Cu has been known to exhibit higher adsorption of the proton, thus by replacing Ni with Cu in NiFe LDH shows potential for enhancing the chemical kinetics of HER due to filled d-orbitals and electron transfer. Here, we first demonstrate a strategy of modulating the electronic structure of CuFe LDH, by manipulating Cu/Fe ratio and nanostructure, to improve the HER catalysis of single layer and cost-effective transition metal LDHs in AE. The atomic allocations of Cu and Fe based on the proposed method in the synthesis of LDH allows for optimizing the proton and hydroxide adsorption during electrocatalysis, where the CuFe LDH generate a current density of − 10 mA cm-2 at the overpotential of − 110 mV and a highly enhanced electrolysis stability at − 100 mA cm-2. Meanwhile, a low overpotential of 257 mV (10 mA cm-2) is achieved. Advanced spectroscopic characterizations, including X-ray photoelectron spectroscopy, confirms the electronic structure modulation with adjustment of Cu/Fe ratio; and the synchrotron sourced X-ray absorption spectroscopy unambiguously confirm the higher electron density of Cu and the unique M-O(H)-M’ structure that enhances water splitting by facilitating ion adsorption and electron transfer. The cathodic activation energy of 14.34 kJ mol-1 is achieved by higher electronic density due to electronic modulation of the catalyst structure. This work demonstrates the insights of electronic structure modulation for the rational design of efficient catalysts without noble or rare-earth metals for HER.

NiAl‐LDH In‐Situ Derived Ni2P and ZnCdS Nanoparticles Ingeniously Constructed S‐Scheme Heterojunction for Photocatalytic Hydrogen Evolution

AbstractSurface modification of photocatalytic materials is a good choice for improving semiconductor activity. Simple surface modification strategy and abundant active site construction are the key factors to improve photocatalytic activity. Take NiAl‐LDH as the matrix, perform partial phosphating, and use the spatial confinement effect to generate highly dispersed Ni2P. Ni2P does not exist independently but on the 3D NiAl‐LDH's surface. The introduction of NiAl‐LDH‐P can improve the utilization of Zn0.5Cd0.5S on solar energy and speed up the transfer rate of photogenerated carriers. Ni2P makes the active sites of phosphide more abundant, and the unique electron distribution of phosphide is conducive to photon capture, thus accelerating the hydrogen precipitation rate in the composite photocatalyst. Partial phosphating retains the 3D framework of hydrotalcite. The well‐dispersed 0D to 3D S‐scheme heterojunction hybrid material is composed of three‐dimensional nano‐flowers and tiny nano‐particles alternately formed by countless nano‐sheets. The multi‐dimensional structured composite photocatalyst has abundant active sites, large specific surface area, and strong proton adsorption capacity, thus exhibiting more excellent photocatalytic hydrogen evolution performance. The maximum hydrogen production of the composite photocatalyst under 5 W LED simulated visible light for 5 h can reach 1982.43 μmol (39.64 mmol g−1 h−1) and the apparent quantum efficiency reached 6.22 % at 475 nm. The construction of the Zn0.5Cd0.5S/NiAl‐LDH‐P S‐scheme heterojunction changes the hydrogen evolution site from Zn0.5Cd0.5S to Ni2P, so that the conduction band position of the composite photocatalyst becomes higher, the reduction ability is enhanced, and the hydrogen evolution The site changed from Zn0.5Cd0.5S to Ni2P, which is more conducive to the generation of hydrogen, thereby improving the activity and stability of hydrogen production. The space design of 0D and 3D provides new thinking for the design of the closely contacted S‐scheme heterojunction photocatalytic. The application of surface modification strategies and the construction of abundant active sites point out the direction for further improving the composite photocatalytic activity.