Hydrogen Adsorption Research Articles

Boron nitride graphite intercalated with carbon-boron-nitride fullerenes for enhanced hydrogen storage

The hydrogen storage of boron nitride graphite intercalated with carbon-boron-nitride fullerenes was investigated using density functional theory and Grand Canonical Monte Carlo simulations. At 77 K and 30 MPa, the optimized structures C14(BN)23-inserted BN graphite material achieved a gravimetric hydrogen adsorption of 6.39 wt% and a volumetric adsorption of 0.07 kg/L, surpassing the U.S. Department of Energy’s targets of 5.5 wt% and 0.04 kg/L, respectively. This improved performance is attributed to the stronger adsorption affinity of BN atoms and the increased lattice constants of the material. These findings offer promising avenues for the development of advanced hydrogen storage materials.

Sparkling Synergy: Enhancing Hydrogen Evolution with a Mesoporous CoP/FeP Interface.

The reaction kinetics is predominantly determined by the surface and interface engineering of electrocatalysts. Herein, we demonstrate the growth of cobalt monophosphide and iron monophosphide (CoP/FeP) with an effective solid interface. The surface of CoP/FeP is mesoporous, which is obtained by phosphidizing mesoporous CoFe2O4. The CoP/FeP electrode exhibits substantially superior hydrogen evolution reaction (HER) performance compared to CoP and FeP. The overpotentials (η) required to generate 10 mA cm-2 are determined to be around 98 mVRHE (CoP/FeP), 220 mVRHE (FeP), and 265 mVRHE (CoP) in an acidic electrolyte. The exchange current density and Tafel slopes suggest that CoP/FeP has better redox properties and kinetic abilities compared to FeP and CoP. Furthermore, the CoP/FeP electrode exhibits reduced electrochemical impedance and superior surface charge transport characteristics in comparison to both the CoP and FeP electrodes. In addition to having a greater number of catalytically active sites, the turnover frequency of CoP/FeP is approximately 2 and 5 times higher than that of FeP and CoP, respectively. The CoP/FeP electrode maintains a consistent current density of around 25 mA cm-2 for a continuous period of 24 h during the HER, attesting to the excellent durability of the CoP/FeP electrode. In addition, a relationship between differential hydrogen adsorption energy (ΔEH), the corresponding Gibbs free energy change (ΔGH), and the hydrogen coverage on distinct surfaces, namely, CoP, FeP, and CoP/FeP, is established. The calculation findings show that the CoP/FeP surface, which is predominantly exposed with CoP, exhibits the highest catalytic potential for the HER. The estimation of the specific HER activity of the electrodes, normalized to the electrochemically active surface area, corroborates the calculation findings.

Ingenious regulation and activation of sites in the 2H-MoS2 basal planes by oxygen incorporation for enhanced photocatalytic hydrogen evolution of CdS

The 2H phase of MoS2 has the advantages of stable phase structure and tunable preparation approach, while the unfavorable H adsorption ability at the basal plane sites hinders the H2 evolution performance. Here, we developed an effective strategy for the regulation of the basal plane properties of MoS2 via oxygen doping. It is demonstrated that the Gibbs free energy of hydrogen adsorption (ΔGH*) at the sites in the basal plane can be effectively optimized. Using oxygen-doped MoS2 (OMoS) as a cocatalyst, the constructed OMoS/CdS heterojunction photocatalyst shows a stronger built-in electric field and improved photocatalytic H2 production activity. The optimized OMoS/CdS sample with only 0.3 wt% OMoS loading amount achieved an H2 evolution rate of 58.47 mmol g-1h−1 under AM 1.5 light irradiation, which is significantly superior to that of conventional MoS2 modified CdS and even higher than the 1 wt% Pt modified CdS. Our results not only highlighted the significant potential of OMoS as a photocatalyst for hydrogen production, but also proposed a superior to and effective conception for optimizing the H2 evolution activity at the basal plane sites of 2H-MoS2.

Physically activated resorcinol-formaldehyde derived carbon aerogels for enhanced hydrogen storage

Carbon aerogels have great potential as hydrogen storage materials owing to their exceptional specific surface area, low weight, and high porosity. These characteristics improve the ability to increase hydrogen adsorption capacity, making them promising candidates for hydrogen storage materials. Nevertheless, the implementation encounters obstacles such as limited storage capacity under ambient temperature and pressure. The present study reports the improved hydrogen storage capacity of carbon aerogels synthesized by Pekala's sol-gel method and optimized by physical activation. This study aims to optimize specific surface area and micropore volumes by physical activation to enhance hydrogen adsorption via the physisorption mechanism. The as-synthesized carbon aerogel has a specific surface area of 579.53 m2/g with a pore volume of 0.34 cm3/g whereas this surface area and pore volume have been tuned using its physical activation. The physically activated carbon aerogel shows a significantly higher specific surface area of 799.68 m2/g with a pore volume of 0.47 cm3/g as compared to the pristine carbon aerogel. This optimization in the specific surface area has enhanced the hydrogen storage capacity of carbon aerogel. The activated carbon aerogel exhibits a promising hydrogen storage capacity of 5.28 wt% at liquid nitrogen temperature under a hydrogen pressure of 22 atm whereas 3.39 wt% of hydrogen storage capacity has been seen in the unactivated carbon aerogel under the same conditions. In addition, activated carbon aerogel showed good hydrogen adsorption and desorption kinetics up to 30 cycles at room temperature (27 °C) under 22 atm hydrogen pressure. The reason behind enhanced hydrogen adsorption capacity in activated carbon aerogel has been put forward using various characterization techniques like XRD, TEM, SEM, and BET and discussed in the mechanism section.

Alkali Metal‐Doped Fullerenes as Hydrogen Storage—A Quantum Chemical Investigation

AbstractThe quest for alternative energy sources has been spurred by the drawbacks and environmental risks of fossil fuels, with hydrogen emerging as a viable contender. But finding materials that can effectively store hydrogen with the best adsorption energy is a major obstacle to building a hydrogen‐based economy. As a result, a significant amount of research has been conducted worldwide to examine fullerene's (C60) potential for hydrogen adsorption. The results of extensive DFT calculations are presented here, pertaining to the adsorption of hydrogen molecules onto fullerenes doped with alkali metals, namely Rubidium (Rb), Ceasium (Cs), and Fransium (Fr). The study analyzes a number of parameters, such as global properties, electronic, optical, and surface annihilation energy. These analyses are performed using the Gaussian 09 simulation package with the 6–31G/B3LYP level of theory DFT methodology. The findings show that an exothermic process is involved in the adsorption of hydrogen onto fullerene doped alkali elements, as evidenced by the negative adsorption energy. The attractive interactions between the polarized dipole of hydrogen molecules and the surface dipole of doped fullerenes can be the cause of this exothermicity. These results imply that fullerenes decorated with alkali metals are promising as likely hydrogen storage media.

Manipulating nano-WS2 aggregates in electroplated Ni coating to mitigate hydrogen embrittlement in X70 pipeline steel

WS2 is a two-dimensional nanomaterial with significant potential for hydrogen barrier applications. Herein, WS2/Ni composite coatings were fabricated on X70 pipeline steel substrates via electrodeposition. The properties of the composite coatings were systematically examined by electrochemical hydrogen permeation tests, hydrogen evolution kinetics tests, SSRT, SKPFM, and FEM. The results indicate that varying the deposition time leads to changes in coating microstructure, which correspondingly influence hydrogen permeation performance. Furthermore, the hydrogen barrier mechanism of the WS2/Ni composite coatings involves two key processes: the inhibition of hydrogen evolution reactions on the coating surface and hydrogen adsorption by WS2 within the coating interior.

Hydrogen activation and surface exchange over La0.8Sr0.2Ga0.8Mg0.2O3-z

Hydrogen mass-transfer between molecular hydrogen and La0.8Sr0.2Ga0.8Mg0.2O3-z (LSGM) has been studied by means of hydrogen isotope exchange with gas phase equilibration. The measurements were carried out within a temperature range of 300–700 °C, with molecular hydrogen pressures of 100, 150 and 200 Pa. It was found that LSGM is capable of consuming hydrogen from the gas phase. The relative number of hydrogen atoms in the LSGM structure varied between 1 and 4 mol.%. The kinetics of hydrogen isotope redistribution revealed that the mass-transfer mechanism between molecular hydrogen in the gas phase and LSGM includes at least three steps. The first two relate to dissociative and associative/molecular adsorption of molecular hydrogen, while the third, identified as the rate-determining step in the exchange process, relates to hydrogen incorporation into LSGM structure. The kinetic and thermodynamic isotope effects of the exchange were estimated.

Construction of 0-dimensional silver quantum dot/MoSe2@MXene/3-dimensional porous copper foam composite electrodes with heterogeneous interfaces for synergistic electrocatalytic degradation of antibiotics

This study proposes a novel and efficient Ag quantum dots (QDs)/MoSe2@two-dimensional transition metal carbide/nitride (MXene)/copper foam (CF) composite electrode to address the challenge of electrocatalytic degradation of antibiotics in water. The electrode formed a unique electron donor–acceptor system by loading Ag QDs and heterostructured nanosheets on CF, significantly facilitating charge transfer and segregation at the interface. The catalytically active sites at the edges and defective locations of MoSe2 in conjunction with the two-dimensional MXene structure, which formed an efficient electron transfer channel, promoted the electron transfer from the interior to the surface and accelerated the hydrogen adsorption and reduction reactions. Moreover, the charge redistribution at the interface of Ag QDs and MoSe2@MXene formed interfacial dipoles, increasing the active sites on the catalyst surface and promoting the generation of cathodic atomic hydrogen (H*). Under optimal conditions, the degradation rate of tigecycline (TGC) reached as high as 90.1 % ± 2.4 % within 60 min. The anode-generated OH and HClO, along with the cathode-generated H, further promoted the degradation of TGC through co-catalysis. The degradation pathways were analyzed using density-functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS) techniques. Moreover, toxicity analysis of the degradation products was carried out to ensure the safety of the treated wastewater discharge. A reflux continuous effluent reactor was also designed to achieve high degradation efficiency and low energy consumption after stable operation, laying the foundation for industrial applications. This technology provides new ideas for the design of green, efficient, stable, and low-consumption electrocatalytic reactors and contributes to a sustainable future environment.

Investigation of the hydrogen adsorption properties on titanium metal under vacuum conditions

Investigation of the hydrogen adsorption properties on titanium metal under vacuum conditions

Integrated experimental and DFT-based study on pH-dependent photoelectrochemical performance of Ca2Fe2O5

In this study, photoelectrochemical (PEC) performance of Ca2Fe2O5 nanoflakes were explored to understand corrosion and degradation tendency. Ca2Fe2O5 nanoflakes were synthesized via a modified two step thermochemical method consisting of hydrothermal reaction and chemical conversion. Detailed characterization using SEM, XRD, and TEM confirmed the highly crystalline and (200) faceted Ca2Fe2O5 nanoflake morphologies. PEC measurements, conducted in six distinct electrolyte conditions, revealed significant photocurrent variations with respect to pH change, highlighting pH 11 as the optimal environment. Electrochemical impedance spectroscopy (EIS) was applied to elucidate charge transfer rate depending on the hydrogen evolution reaction (HER) mechanisms. Furthermore, DFT calculations provided insights into the surface interactions of Ca2Fe2O5 with hydrogen and hydroxide absorbates, elucidating the electronic and structural change during PEC reactions. The simulation demonstrated that, while hydrogen adsorption induced Fe-O bond dissociation, hydroxide adsorption showed minimal effect on surface bonds. HER overpotentials were calculated for both Tafel and Volmer step, elucidating the facile and stable HER in OH terminated surface environments. These findings underscore the importance of alkaline electrolyte environment in optimizing the PEC stability and efficiency of Ca2Fe2O5 photocathodes.

Modulating the Electronic Structure of Cobalt-Vanadium Bimetal Catalysts for High-Stable Anion Exchange Membrane Water Electrolyzer.

Modulating the electronic structure of catalysts to effectively couple the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for developing high-efficiency anion exchange membrane water electrolyzer (AEMWE). Herein, a coral-like nanoarray composed of nanosheets through the synergistic layering effect of cobalt and the 1D guiding of vanadium is synthesized, which promotes extensive contact between the active sites and electrolyte. The HER and OER activities can be enhanced by modulating the electronic structure through nitridation and phosphorization, respectively, enhancing the strength of metal-H bond to optimize hydrogen adsorption and facilitating the proton transfer to improve the transformation of oxygen-containing intermediates. Resultantly, the AEMWE achieves a current density of 500 mA cm-2 at 1.76 V for 1000 h in 1.0 M KOH at 70°C. The energy consumption is 4.21 kWh Nm-3 with the producing hydrogen cost of $0.93 per kg H2. Operando synchrotron radiation and Bode phase angle analyses reveal that during the high-energy consumed OER, the dissolution of vanadium species transforms distorted Co-O octahedral into regular octahedral structures, accompanied by a shortening of the Co-Co bond length. This structural evolution facilitates the formation of oxygen intermediates, thus accelerating the reaction kinetics.

Machine learning prediction of hydrogen adsorption energy on platinum nanoclusters: A comparative study of SOAP descriptors

Hydrogen binding energy in metal materials is of high significance in the hydrogen storage as well as the hydrogen evolution reaction of electrocatalysis. In this work, the datasets (more than 9000 data) of hydrogen adsorbed on Pt nanoclusters with different sizes are obtained by first-principles calculations. Data analysis shows that the binding strength of hydrogen with Pt is closely relevant to the local structures of the adsorption sites. The local features of the distance between the platinum and hydrogen and the size of the nanoclusters are supplemented to the Smooth Overlap of Atomic Positions descriptors to fit and predict the adsorption energies of hydrogen on different Pt nano-structures by performing the machine learning method. Gaussian Process Regression (GPR) and Random Forest Regressor (RFR) are used to construct the prediction model of hydrogen binding energies and it is found the R2 of test set is improved from 0.63 to 0.78 with modified descriptors. By applying it into other nanoclusters, the MAE of the prediction model is 0.08 eV, which exhibits high accuracy of the hydrogen adsorption energy. Our model can be easily extended to the prediction of hydrogen adsorption energy of other materials with affordable computational cost and accuracy, which would be helpful for the structural design of high-performance catalysts.

In-situ exfoliating graphene to anchor Mo2C NPs and modulate crystal planes for hydrogen production

An economical and efficient noble metal-free catalyst is necessary for large-scale hydrogen production. Here, Mo2C nanoparticles (NPs) were well-dispersed on the surface of 2D graphene nanosheets by in-situ propping oxide graphene (GO) layers, anchoring molybdate ions between GO layers and pyrolysis. The exposed crystal planes were also adjusted by above strategy. The results indicate that uniform and well-dispersed Mo2C NPs with a narrow size distribution were anchored on 2D rGO nanosheets and exposed dual crystal planes. The results of hydrogen evolution reaction (HER) show that the optimal Mo2C/rGO catalyst only needs low overpotential (η10, 112 mV) to drive 10 mA cm−2 in alkaline solution, and η10 only increased by 12 mV after 1000 cycles test, indicating high activity and stability for HER. Notably, the overpotential is below than that of Pt/C commercial catalyst when current density is more than 100 mA cm−1. The excellent performance is benefit from low hydrogen adsorption Gibbs free energy (ΔGH∗) on the Mo2C catalyst. Therefore, the proposed strategy is efficient to prepare well-dispersed and dual crystal planes-exposed Mo2C NPs for electrocatalytic hydrogen evolution.

Facile synthesis of dual-MOF ultrathin nanosheets supported on layered double hydroxides heterostructure: Electron modulation strategy for enhanced electrocatalytic water splitting

In this study, we achieved electron environment modulation of MOF-based electrocatalyst by creating a dual-functional heterostructure using two-dimensional (2D) MOFs and layered double hydroxides (LDH), to enhance its electrocatalytic performance. Through a self-sacrificial template method, ultrathin hybrid dual-MOF (CoBDC and MIL-100(Fe)) nanosheets were grown on LDH, forming DM@CoFeRu-LDH, a 2D heterostructure benefiting from interference co-growth on the 2D scaffold. The thickness of dual-MOF nanosheets can be controlled by regulating the nucleation and reaction kinetics. Specifically, with a thickness ranging from 1–1.5 nm, it effectively exposes more active sites and accelerate electron and mass transfer. Additionally, electron transfer occurred between the dual-MOF and LDH heterostructures, leveraging synergistic effects from multi-metal centers to achieve an optimal electron structure. DM@CoFeRu-LDH exhibited the lowest energy barrier for the rate-determining step in the oxygen evolution reaction, along with a favorable hydrogen adsorption energy for the hydrogen evolution reaction. As a result, the DM@CoFeRu-LDH demonstrated efficient electrocatalytic activity, requiring only a voltage of 1.50 V to achieve a current density of 10 mA cm−2.

Designing Mo-based transition metal dichalcogenides for sustainable hydrogen production: Anionic substitution and DFT insight

Anionic substitution is an effective approach to optimize the catalytic activity of Mo based transition metal dichalcogenide (TMD)- MoS2 towards hydrogen evolution reaction (HER). By optimizing the S-to-Se ratio, materials with the ideal Gibbs free energy of hydrogen adsorption (ΔGH) values are synthesized (MoS2, MoS1.4Se0.6, MoS1.2Se0.8, MoSSe, MoSe2) and their HER performance is examined in 0.5 M H2SO4 solution. Density functional theory calculations of hydrogen adsorption energy on the surface of the electrocatalysts show that Se substitution facilitates electron transfer between the catalyst surface and the hydrogen donor, thereby lowering the additional potential required for water splitting, making MoS1.2Se0.8 the most favorable HER electrocatalyst with the lowest value of adsorption energy. Further enhancement in the electrocatalytic activity of mixed anion TMDs has been achieved by the incorporation of carbon nanotubes (CNTs). MoS1.2Se0.8-CNT nanocomposite exhibits superior HER performance with an overpotential of 118 mV and a Tafel slope of 63 mV/decade as compared to MoS1.2Se0.8 sample owing to the synergetic effect from CNTs and MoS1.2Se0.8.

Strong electronic metal-support interaction of Ni4Mo/N-SrMoO4 promotes alkaline hydrogen electrocatalysis

Ni4Mo electrocatalyst stands out as the promising candidate for hydrogen evolution/oxidation reaction (HER/HOR), yet the intensive hydrogen adsorption leads to sluggish kinetics, decreasing hydrogen catalysis efficiency. Herein, the structure of Ni4Mo nanoparticles anchored on wafer-biscuit-like N-SrMoO4 nanorods (Ni4Mo/N-SrMoO4) is developed to accelerate reaction kinetics by modulating electronic structure. The designed N-SrMoO4 support enables strong electronic metal-support interaction with Ni4Mo, resulting in a downward shift of d-band center and achieving thermally neutral hydrogen adsorption. Ni4Mo/N-SrMoO4 exhibits HER performance with an ultralow overpotential of 15 mV at 10 mA cm−2, superior to Pt/C (η10=18 mV). The outstanding exchange current density of 10.2 mA cm−2 for HOR is three times higher than that of Pt/C (3.5 mA cm−2). Ni4Mo/N-SrMoO4 is further assembled in anion exchange membrane water electrolyzer (AEMWE), resulting in a current density of 100 mA cm−2 at voltage of 1.71 V and the excellent stability of 300 hours. Theoretical calculations and in-situ spectroscopy indicate that the introduction of Sr in N-SrMoO4 effectively enhances electronic metal-support interaction, facilitates the enrichment of adsorbed hydroxyl (OHads) on active sites and weakens hydrogen adsorption on Ni4Mo, thereby accelerating reaction kinetics of hydrogen electrocatalysis.

Enhancing HER catalyst screening of modified MXenes through DFT and machine learning integration

AbstractMXenes doped with non‐metallic and transition metal elements exhibit remarkable potential as catalysts in the hydrogen energy. Nonetheless, efficiently identifying viable materials from a vast array of candidates remains a formidable challenge. Here, we conducted density functional theory (DFT) calculations to obtain the hydrogen adsorption free energy () of 78 types of doped TiVCO2 MXene catalysts. Then we employed machine learning models to categorize the values of the 78 catalysts, resulted in an accurate model which only uses 7 readily available elemental features but has an impressive accuracy of 93.6%. Our model successfully predicting 5 TiVCO2 catalysts doped with S with superior performance, subsequently validated through DFT calculations. This classification methodology not only evaluates the range of effectively but also facilitates qualitative prediction and screening of catalysts, presenting a novel approach for catalytic systems with limited available data.

Adsorption of Atomic Hydrogen on Hydrogen Boride Sheets Studied by Photoelectron Spectroscopy.

Hydrogen boride (HB) sheets are emerging as a promising two-dimensional (2D) boron material, with potential applications as unique electrodes, substrates, and hydrogen storage materials. The 2D layered structure of HB was successfully synthesized using an ion-exchange method. The chemical bonding and structure of the HB sheets were investigated using Fourier Transform Infrared (FT-IR) spectroscopy and Transmission Electron Microscopy (TEM), respectively. X-ray photoelectron spectroscopy (XPS) was employed to study the chemical states and transformation of the components before and after atomic hydrogen adsorption, thereby elucidating the atomic hydrogen adsorption process on HB sheets. Our results indicate that, upon atomic hydrogen adsorption onto the HB sheets, the B-H-B bonds were broken and converted into B-H bonds. This research highlights and demonstrates the changes in chemical states and component transformations of the boron element on the HB sheets' surface before and after atomic hydrogen adsorption, thus providing a clearer understanding of the unique bonding and structural characteristics of the HB sheets.

Design of NiPS3/MoS2/rGO hybrid electrocatalyst for electrochemical hydrogen evolution

The design and development of efficient electrocatalysts for hydrogen evolution reaction is presently a pressing task to overcome future energy demands. In the present study a hybrid layered compound NiPS3/MoS2/rGO (NMR) is investigated as an electrocatalyst for hydrogen evolution reaction (HER). The metal trichalcogenidophosphates (MTPs), transition metal dichalcogenides and reduced graphene oxide materials based electrocatalysts are promising material for HER. The hybrid layered compound NMR displays good electrocatalytic activity in acidic medium in comparison to its counterparts MoS2/rGO and NiPS3/rGO with an overpotential and Tafel slope of 152 mV vs RHE and 75 mV/dec, whereas MoS2/rGO and NiPS3/rGO shows an overpotential of 206 mV and 223 mV vs RHE with a Tafel slope value of 146 mV/dec and 154 mV/dec respectively. The hybrid electrocatalyst exhibited high stability up to 1000 cycles with a stable current. The high HER activity of NMR is attributed to synergistic effect of electrocatalysts where P and S of NiPS3 acts as an appropriate hydrogen adsorption sites and catalytically active Mo edge sites of MoS2 with high charge carrier property of rGO contributed to enhanced hydrogen evolution reaction.

Unlocking Efficient Alkaline Hydrogen Evolution Through Ru-Sn Dual Metal Sites and a Novel Hydroxyl Spillover Effect.

Alkaline hydrogen evolution reaction (HER) has great potential in practical hydrogen production but is still limited by the lack of active and stable electrocatalysts. Herein, the efficient water dissociation process, fast transfer of adsorbed hydroxyl and optimized hydrogen adsorption are first achieved on a cooperative electrocatalyst, named as Ru-Sn/SnO2 NS, in which the Ru-Sn dual metal sites and SnO2 heterojunction are constructed based on porous Ru nanosheet. The density functional theory (DFT) calculations and in situ infrared spectra suggest that Ru-Sn dual sites can optimize the water dissociation process and hydrogen adsorption, while the existence of SnO2 can induce the unique hydroxyl spillover effect, accelerating the hydroxyl transfer process and avoiding the poison of active sites. As results, Ru-Sn/SnO2 NS display remarkable alkaline HER performance with an extremely low overpotential (12mV at 10mA cm-2) and robust stability (650h), much superior to those of Ru NS (27mV at 10mA cm-2 with 90h stability) and Ru-Sn NS (16mV at 10mA cm-2 with 120h stability). The work sheds new light on designing of efficient alkaline HER electrocatalyst.