H2 Absorption Research Articles

Metal Hydride Composite Structures for Improved Heat Transfer and Stability for Hydrogen Storage and Compression Applications

Metal alloys and intermetallic compounds offer an attractive method for safely storing hydrogen (H2). The metal alloys absorb H2 into their structure, often swelling and fracturing as a result of phase transformation during hydride formation/decomposition cycles. The absorption of H2 is an exothermic process, requiring the effective and efficient removal of heat. This can be challenging as heat transfer to/from powdered beds is notoriously difficult, and often limited by poor thermal conductivity. Hence, the observed reaction kinetics for absorption and desorption of H2 is dominated by heat flow. The most common method for improving the thermal conductivity of the alloy powders is to prepare them into composite structures with other high thermal conductivity materials, such as carbons and expanded natural graphite. Such composite structures, some also combined with polymers/resins, can also mitigate safety issues related to swelling and improve cyclic durability. This paper reviews the methods that have been used to prepare such composite structures and evaluates the observed impact on thermal conductivity.

Achieving excellent CO2 poisoning resistance of ZrCo hydrogen isotope storage material by surface reconstruction strategy

ZrCo alloy has been treated as the most promising candidate for hydrogen isotope storage in the International Thermonuclear Experimental Reactor (ITER). However, its poisoning resistance properties still remain challenging since the presence of impurity gas of CO2. Herein, the poisoning resistance behaviors and mechanism of ZrCo in H2+CO2 mixed gas were systematically investigated. Surprisingly, even trace amounts of CO2 can strongly deteriorate hydrogenation kinetics of ZrCo, which can be mitigated by further increasing the inputting pressure of the mixed gas. Such poisoning phenomenon can be attributed to the selective preferential absorption of CO2 on the ZrCo surface. Namely, the absorbed CO2 occupies the active sites on the surface and thus significantly blocks the absorption or dissociation of H2. Therefore, we proposed an in-situ surface reconstruction strategy by high-temperature treatment at 550 °C in H2+CO2 mixed gas. Specifically, in-situ formed metallic Co nanoclusters were generated on ZrCo surface, which are not only tough to be poisoned by CO2 contamination, but also can function as the catalytic active sites for H2 dissociation. Thus, an enhanced CO2 poisoning tolerance of ZrCo was achieved through the novel in-situ surface reconstruction strategy.

In situ diffraction studies of phase-structural transformations in hydrogen and energy storage materials: An overview

The paper presents an overview of advanced in situ diffraction studies as a highly valuable tool to probe the structure and reacting mechanisms of hydrogen and energy storage materials. These studies offer benefits from the use of a high flux diffraction beam in combination with high resolution measurements, and allow, even when using very small samples, establishing the mechanism of the phase-structural transformations and their kinetics based on a rapid data collection for the various charge-discharge states at variable test conditions. The applied conditions include a broad range of hydrogen/deuterium pressures, from vacuum to high pressures reaching 1000 bar H2/D2, and temperatures, from cryocooling (2 K) to as high as 1273 K (1000 °C). Simultaneously, various state-of-charge and discharge are probed when studying metal-H/D systems for hydrogen/deuterium gas storage and as anode electrodes of metal hydride batteries. The range of the studied systems includes but is not limited to the AB5, AB2 Laves type, AB, equiatomic ternary ABC intermetallics and Mg-containing layered AB3 structures and composites. Prospects on Li-ion full cells are considered as well. Interrelations between the structure and hydrogen storage performance, including maximum and reversible H storage capacity, hysteresis of hydrogen absorption and desorption, H2 absorption and desorption in dynamic equilibrium conditions, are considered and related to the ultimate goal of optimisation of the H storage behaviours of the advanced H storage materials. Numerous contributions of Dr. Michel Latroche to the field are highlighted, particularly in in situ studies during electrochemical transformations. The paper summarises a long-standing collaboration of the co-authors in the field, which also included 29 joint topical publications with Dr. Michel Latroche, and references 163 original publications.

Assisting Ni catalysis by CeO2 with oxygen vacancy to optimize the hydrogen storage properties of MgH2

Although MgH2 has been widely regarded as a promising material for solid-state hydrogen storage, its high operating temperature and slow kinetics pose a major bottleneck to its practical application. Here, a nanocomposite catalyst with interfacial coupling and oxygen defects, Ni/CeO2, is fabricated to promote H2 desorption and absorption properties of MgH2. The interface of Ni/CeO2 contributes to both strong mechanical coupling towards stabilizing partial Ni and electronic coupling towards inducing a high concentration of oxygen vacancies in CeO2. Theoretical calculations evidence that CeO2 with oxygen vacancy assist Ni in weakening the energy of Mg-H bond as well as enhancing the adsorption energy of Ni upon hydrogen atoms, and the extent of this assistance surprisingly increases with increasing oxygen vacancies concentration. As a result, an impressive performance is achieved by MgH2-5 wt.% Ni/CeO2 with onset desorption temperature of only 165 °C, and it absorbs approximately 80% hydrogen in just 800 s at 125 °C. The generation mechanism of intermediate active species concerning Ni/CeO2 in different states has been analyzed for the first time, and the relationship between interfacial coupling and phase evolution has been elucidated. Therefore, a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed. It is believed that this work provides a unique perspective on the mechanism of interfacial coupling and the generation of defects in composite catalysts.

Correlations between H2 Permeation and Physical/Mechanical Properties in Ethylene Propylene Diene Monomer Polymers Blended with Carbon Black and Silica Fillers.

H2 permeation in peroxide-crosslinked EPDM blended with carbon black (CB) and silica fillers was studied at pressures ranging from 1.2 MPa to 90 MPa via the volumetric analysis technique. H2 uptake in the CB-filled EPDM revealed dual-sorption behaviors via Henry's law and the Langmuir model, which were attributed to H2 absorption by the polymer chains and H2 adsorption at the filler interfaces, respectively. Additionally, single-sorption mechanisms were observed for neat EPDM and silica-blended EPDM according to Henry's law, indicating H2 absorption by the polymer chain. The linear decreases in the diffusivity with filler content for the silica-blended EPDMs were attributed to increases in the diffusion paths caused by the filler. Exponential decreases in the diffusivity with increasing filler content and in the permeation with the physical/mechanical properties for CB-filled EPDMs were caused by decreases in the fractional free volume due to increased densities for the EPDM composites. Moreover, good filler-dependent correlations between permeability and density, hardness, and tensile strength were demonstrated for EPDMs used as sealing materials for O-rings. From the resulting equation, we predicted the permeation value without further measurements. Thus, we can select EPDM candidates satisfying the permeation guidelines used in hydrogen infrastructure for the future hydrogen economy.

Construction of 0D/3D CdS/CoAl-LDH S-scheme heterojunction with boosted charge transfer and highly hydrophilic surface for enhanced photocatalytic hydrogen evolution and antibiotic degradation

Energy band matching coupled with intimate interface in a heterojunction is the prerequisite for achieving the separation of photogenerated carriers. Herein, 0D CdS nanospheres were uniformly anchored in 3D flower-like CoAl layered double hydroxide (CoAl-LDH) spheres via a hydrothermal process. The unique porous structure and abundant hydrophilic groups can significantly promote the interactions between catalyst and solutions and thus facilitate the photocatalytic reaction. The appropriately staggered band structures can trigger the formation of S-scheme heterojunction, and the tight connection between the CdS and CoAl-LDH offers more charge transport channels, thereby accelerating the charge transfer. The optimized CdS/CoAl-LDH nanohybrid presents a photocatalytic hydrogen evolution of 6.19 mmol/g/h and tetracycline hydrochloride (TC) degradation efficiency of 92.2 % in 50 min. Moreover, the Cd2+ ion concentration measured by ICP-OES verifies the alleviation of photocorrosion, and the DFT calculations further demonstrate the higher hydrophilia, lower H2 absorption energy and stronger charge interactions of CdS/LDH hybrid. This work provides a feasible strategy to efficiently utilize the photoinduced carries by constructing a highly hydrophilic S-scheme heterojunction.

Direct evidence of hydrogen absorption from the skin – a pig study

IntroductionIt has not been experimentally proven whether hydrogen gas (H2) is absorbed into the body through the skin by hydrogen-rich hot-water bathing.Material and methodsIn this study, Hairless mini pigs, whose skin closely resembles that of humans, were bathed in hydrogen (H2)-rich hot water to assess the absorption of H2 through the skin. An H2-rich water generation line was developed to maintain a high concentration of H2 via the circulation of hot water in an 80-litre bathtub. Two hairless mini pigs (14.2 ±1.4 kg, 60 days old, 1 male and 1 female) were first placed in the H2-dissolved bath. After a washout period, one pig was bathed in an H2-dissolved bath and the other in a bath containing no H2 for 20 min. During the experiment, blood was collected from the pigs’ jugular vein, carotid artery, inferior vena cava (IVCs), and portal vein to measure the blood H2 concentration.ResultsThe H2 concentration at the IVC of the pig in the H2-dissolved bath increased from 0.733 ±0.636 ppb (w/w) to 16.9 ±4.46 ppb (w/w) after 2 min, 37.2 ±13.8 ppb (w/w) after 10 min, and 45.7 ±7.73 ppb (w/w) (H2 saturation level: 3%) after 20 min. The blood H2 concentration levels of the pig in the non-H2 bath remained below the detection limit of 0.3 ppb.ConclusionsBathing in water with a high concentration of dissolved hydrogen was considered an effective means of supplying H2 to skin tissues and beyond.

Thermoelectric Detection of H2 Gas Based on Exothermic Absorption by Pd

The thermoelectric hydrogen (H2) gas sensor using PCB (Printed Circuit Board) technique was developed based on the exothermic absorption of H2 by a palladium (Pd) film coated on a thermocouple. A cascade connection of two thermocouples composed of copper (Cu) and constantan (55% nickel and 45% Cu) was used to detect the exothermic absorption of H2 by Pd. The differential thermoelectric voltage output between the two thermocouples (with and without the Pd film) increased linearly with the H2 gas concentration in a 2.0–50 vol% ambient atmosphere. Standard deviations (SD) for 8 measurement cycles are typically 1.1% at 4 vol% H2, 0.81% at 6 vol% H2, and 1.9% at 8 vol% H2, respectively. The differential thermoelectric voltage output can be detected from 2.0 vol% H2 atmosphere. The ambient temperature fluctuations on the measurement was also effectively reduced using the cascade connection of two thermocouples. Calibration line of H2 concentration calculated by the least square method is linear and standard error (SE), 0.44 vol%, is smaller than measured value.

Temperature-dependent hydrogen storage mechanism in palladium nanoparticles decorated on multi-walled carbon nanotubes

In this study, Palladium (Pd) nanoparticles (NPs) are decorated on the multi-walled carbon nanotubes (MWCNTs) using the chemical reduction method. In situ extended x-ray absorption fine structure (EXAFS) spectroscopy of Pd NPs decorated on MWCNTs is carried out in different temperatures from 77 K up to 540 K to investigate the local structure around the absorber atom Pd, under molecular hydrogen, H2, pressure, and in a vacuum. The Pd K-edge EXAFS gives a deeper insight into the structural properties of Pd-MWCNT compounds under in-situ H2 treatment at various temperatures. EXAFS data show three mechanisms of the interaction of H2 with Pd: the first mechanism involves physical absorption of H2 at low temperatures from 110 to 190 K, the second mechanism includes the formation of PdHx compound at 300 K, and the third mechanism is attributed to the decomposition of PdHx compound at above 400 K. Furthermore, X-ray photoelectron spectroscopy (XPS) results verify the reduction of the palladium oxide after interaction of the sample with molecular hydrogen and the stability of the catalyst under several cycles of annealing and cooling in hydrogen.

Design and performance study on the primary & secondary helical-tube reactor

Using metal hydride (MH) to store hydrogen is developing into an effective approach due to its high hydrogen storage capacity & prominent safety, and MH reactor can significantly advance hydriding & heat transfer rates consequently. In this work, a new primary & secondary helical-tube reactor (P&SHR) is proposed to simplify the reactor structure and improve hydriding rate and heat transfer efficiency, especially near the central H2 tube and inner periphery region of the reactor. The results reveal that P&SHR owns an outstanding H2 uptake performance, which takes less than 500 s to reach its saturated H2 absorption capacity of 99%, saving 300-2700 s hydrogenation time compared with other reactors. Further sensitivity analysis indicates that the structural parameters of P&SHR follow the order: Rp > R′p > Pt > P′t > R′s > Rs > R, whose optimal values are: 18 mm, 2.5 mm, 8 mm, 9 mm, 2.5 mm, 9 mm and 4 mm, respectively. Moreover, the operation parameters including H2 supply pressure, initial temperature and heat transfer coefficient are systematically investigated, conforming that larger H2 pressure and lower fluid temperature tend to promote the driving force and would be beneficial to hydrogenation process and future application scenario for P&SHR.

H2 and CO adsorption ability of cationic lithiated carbenes: A computational study

Quantum chemical calculations have been carried out to investigate the hydrogen and carbon monoxide adsorption characteristics of cationic lithiated carbene complexes. Through the computation of electron density and electron−density−based reactivity descriptors, the nature of interactions related to the bonding between carbene and lithium as well as that between lithium and adsorbed H2 and CO are examined. Calculations reveal that the carbene−Li + complexes can absorb a maximum of four H2 molecules reaching a maximum gravimetric density of 8.8 wt%, whereas, it is found to reach a maximum of 41.3 wt% for the absorption of four CO molecules. The fate of H2 absorption in a carbene−Li+ complex has been studied in the course of a 2000 fs time evolution through Born−Oppenheimer Molecular Dynamics simulation at different temperatures. The outcomes reveal that the H2 molecules are strongly bound at 77 K and get slowly released at elevated temperature.

Performance evaluation of biopolymer mixed matrix membrane for CO2/H2 separation

Hydrogen (H2) energy meets the demand for green and efficient energy; therefore, hydrogen generation, purification, and separation are required. Membrane technology produce ultrapure hydrogen gas using less energy, allowing the process to run continuously. For preparing H2 selective membranes, palladium (Pd) is a potential material because of its high affinity toward H2 absorption. This work modified natural polysaccharide guar gum matric with natural chitosan polymer. The crosslinking of both the polymer improves the tensile strength and elongation at break (%). The composite polymer membrane enhances the separation performance of CO2/N2 by 95.35% and CO2/H2 by 34.29%. Further improvements in CO2/H2, the Pd nanoparticles are incorporated into the composite polymer matrix (GG/CH). The gas permeability data shows a drastic reduction in H2 permeability by incorporating Pd-nanoparticles. In-room temperature, the selectivity of CO2/H2 was obtained 13.06. The morphology of membranes and the presence of Pd nanoparticles in the membrane is characterized by SEM-EDS for confirmation of Pd nanoparticle.

Design of Bifunctional Nb/V Interfaces for Improving Reversible Hydrogen Storage Performance of MgH2

While MgH2 has been widely regarded as a promising solid‐state hydrogen storage material, the high operating temperature and sluggish kinetics pose a major bottleneck for its practical application. Herein, V4Nb18O55 microspheres composed of nanoparticles with size of tens of nanometers are fabricated to promote H2 desorption and absorption properties of MgH2, which results in the uniform formation of Nb/V interfaces based on a molecular scale during the reversible hydrogen storage process. It is experimentally and theoretically demonstrated that the uniform building of Nb/V interfaces not only preserves the ability of Nb in weakening Mg‐H bonds but also alleviates the strong adsorption capacity of metallic Nb toward hydrogen atoms, leading to a relative energy barrier for the whole dehydrogenation process of MgH2 of only 0.5 eV, which is 0.22 and 0.43 eV lower than that of Nb and V, respectively. As a result, under the addition of V4Nb18O55 microspheres, the onset H2 desorption temperature of MgH2 is decreased to 165 °C, 125 °C lower than that of bulk MgH2, and the complete hydrogenation of Mg could be realized even at room temperature, while almost no H2 adsorption is observed for bulk Mg at a high temperature of 50 °C.

Highly Sensitive Hydrogen Sensing Based on Tunable Diode Laser Absorption Spectroscopy with a 2.1 μm Diode Laser

As a new form of energy, hydrogen (H2) has clean and green features, and the detection of H2 has been a hot topic in recent years. However, the lack of suitable laser sources and the weak optical absorption of H2 limit the research concerning its detection. In this study, a continuous-wave distributed feedback (CW-DFB) diode laser was employed for sensing H2. Tunable diode laser absorption spectroscopy (TDLAS) was adopted as the detection technique. The strongest H2 absorption line, located at 4712.90 cm−1 (2121.83 nm, line strength: 3.19 × 10−26 cm−1/cm−2 × molec), was selected. We propose a H2-TDLAS sensor based on the wavelength modulation spectroscopy (WMS) technique and a Herriott multipass gas cell (HMPC) with an optical length of 10.13 m to achieve a sensitive detection. The WMS technique and second harmonic (2f) demodulation technique were utilized to suppress system noise and simplify the data processing. The 2f signal of the H2-TDLAS sensor, with respect to different H2 concentrations, was measured when the laser wavelength modulation depth was at the optimal value of 0.016 cm−1. The system’s signal-to-noise ratio (SNR) and minimum detection limit (MDL) were improved from 248.02 and 0.40% to 509.55 and 0.20%, respectively, by applying Daubechies (DB) wavelet denoising, resulting in 10 vanishing moments. The Allan variance was calculated, and the optimum MDL of 522.02 ppm was obtained when the integration time of the system was 36 s.

Regulation of Kinetic Properties of Chemical Hydrogen Absorption and Desorption by Cubic K2MoO4 on Magnesium Hydride.

Transition metal catalysts are particularly effective in improving the kinetics of the reversible hydrogen storage reaction for light metal hydrides. Herein, K2MoO4 microrods were prepared using a simple evaporative crystallization method, and it was confirmed that the kinetic properties of magnesium hydride could be adjusted by doping cubic K2MoO4 into MgH2. Its unique cubic structure forms new species in the process of hydrogen absorption and desorption, which shows excellent catalytic activity in the process of hydrogen storage in MgH2. The dissociation and adsorption time of hydrogen is related to the amount of K2MoO4. Generally speaking, the more K2MoO4, the faster the kinetic performance and the shorter the time used. According to the experimental results, the initial dehydrogenation temperature of MgH2 + 10 wt% K2MoO4 composite is 250 °C, which is about 110 °C lower than that of As-received MgH2. At 320 °C, almost all dehydrogenation was completed within 11 min. In the temperature rise hydrogen absorption test, the composite system can start to absorb hydrogen at about 70 °C. At 200 °C and 3 MPa hydrogen pressure, 5.5 wt% H2 can be absorbed within 20 min. In addition, the activation energy of hydrogen absorption and dehydrogenation of the composite system decreased by 14.8 kJ/mol and 26.54 kJ/mol, respectively, compared to pure MgH2. In the cycle-stability test of the composite system, the hydrogen storage capacity of MgH2 can still reach more than 92% after the end of the 10th cycle, and the hydrogen storage capacity only decreases by about 0.49 wt%. The synergistic effect among the new species MgO, MgMo2O7, and KH generated in situ during the reaction may help to enhance the absorption and dissociation of H2 on the Mg/MgH2 surface and improve the kinetics of MgH2 for absorption and dehydrogenation.

Detection Feasibility of H2 in Ultra-hot Jupiter Atmospheres

Ultra-hot Jupiters (UHJs) have recently been the focus of several atmospheric studies due to their extreme properties. While molecular hydrogen (H2) plays a key role in UHJ atmospheres, it has not been directly detected on an exoplanet. To determine the feasibility of H2 detection via transmission spectroscopy of the Lyman and Werner bands, we modeled UHJ atmospheres with H2 rotational temperatures varying from 2000 to 4000 K orbiting A-type stars ranging from T eff = 8500 K to T eff = 10,300 K. We present simulated transmission spectra for each planet-star temperature combination while adding Poisson noise varying in magnitude from 0.5% to 2.0%. Finally, we cross-correlated the spectra with expected atmospheric H2 absorption templates for each temperature combination. Our results suggest that H2 detection with current facilities, namely the Hubble Space Telescope, is not possible. However, direct atmospheric transmission spectroscopy of H2 may be viable with future UV-capable flagship missions.

Unveiling the role of carbonate in nickel-based plasmonic core@shell hybrid nanostructure for photocatalytic water splitting

Though carbonates are known for several decades, their role in sun-light driven photocatalysis is still hidden. Herein, carbonate boosted solar water splitting in nickel-based plasmonic hybrid nanostructures is disclosed for the first time via in-situ experiments and density-functional theory (DFT)-based calculations. Ni@NiO/NiCO3 core@shell (shell consisting of crystalline NiO and amorphous NiCO3) nanostructure with varying size and compositions are studied for hydrogen production. The visible light absorption at ∼470 nm excludes the possibility of NiO as an active photocatalyst, emphasizing plasmon driven H2 evolution. Under white light irradiation, higher hydrogen yield of ∼80 µmol/g/h for vacuum annealed sample over pristine (∼50 µmol/g/h) complements the spectroscopic data and DFT results, uncovering amorphous NiCO3 as an active site for H2 absorption due to its unique electronic structure. This conclusion also supports the time-resolved photoluminescence results, indicating that the plasmonic electrons originating from Ni are transferred to NiCO3 via NiO. The H2 evolution rate can further be enhanced and tuned by the incorporation of NiO between Ni and NiCO3.

A 1.46–2.48 μm spectroscopic atlas of a T6 dwarf (1060 K) atmosphere with IGRINS: first detections of H2S and H2, and verification of H2O, CH4, and NH3 line lists

ABSTRACT We present Gemini South/IGRINS observations of the 1060 K T6 dwarf 2MASS J08173001−6155158 with unprecedented resolution ($R\equiv \lambda /\Delta \lambda =45\, 000$) and signal-to-noise ratio (S/N > 200) for a late-type T dwarf. We use this benchmark observation to test the reliability of molecular line lists used up-to-date atmospheric models. We determine which spectroscopic regions should be used to estimate the parameters of cold brown dwarfs and, by extension, exoplanets. We present a detailed spectroscopic atlas with molecular identifications across the H and K bands of the near-infrared. We find that water (H2O) line lists are overall reliable. We find the most discrepancies amongst older methane (CH4) line lists, and that the most up-to-date CH4 line lists correct many of these issues. We identify individual ammonia (NH3) lines, a hydrogen sulfide (H2S) feature at 1.5900 $\mu$m, and a molecular hydrogen (H2) feature at 2.1218 $\mu$m. These are the first unambiguous detections of H2S and H2 absorption features in an extra-solar atmosphere. With the H2 detection, we place an upper limit on the atmospheric dust concentration of this T6 dwarf: at least 500 times less than the interstellar value, implying that the atmosphere is effectively dust-free. We additionally identify several features that do not appear in the model spectra. Our assessment of the line lists is valuable for atmospheric model applications to high-dispersion, low-S/N, high-background spectra, such as an exoplanet around a star. We demonstrate a significant enhancement in the detection of the CH4 absorption signal in this T6 dwarf with the most up-to-date line lists.

A Detection of H2 in a High-velocity Cloud toward the Large Magellanic Cloud

This work presents a new detection of H2 absorption arising in a high-velocity cloud associated with either the Milky Way or the Large Magellanic Cloud (LMC). The absorber was found in an archival Far Ultraviolet Spectroscopic Explorer spectrum of the LMC star Sk-70°32. This is the fifth well-characterized H2 absorber to be found in the Milky Way’s halo and the second such absorber outside the Magellanic Stream and Bridge. The absorber has a local standard of rest central velocity of +140 km s−1 and a H2 column density of 1017.5 cm−2. It is most likely part of a cool and relatively dense inclusion (T ≈ 75 K, n H ∼ 100 cm−3) in a warmer and more diffuse halo cloud. This halo cloud may be part of a still-rising Milky Way Galactic fountain flow or an outflow from the Large Magellanic Cloud.

Ru nanoparticles anchored on porous N-doped carbon nanospheres for efficient catalytic hydrogenation of Levulinic acid to γ-valerolactone under solvent-free conditions

The catalytic transformation of the biomass platform compound levulinic acid (LA) to γ-valerolactone (GVL) is a vital reaction to produce related renewable chemicals and fuels. Developing stable catalysts with highly dispersed and accessible ultrafine metal nanoparticle (NP) active sites for the hydrogenation of LA under solvent-free conditions is still a major challenge. Herein, a versatile nano-emulsion self-assembly method was employed to fabricate N-doped carbon nanospheres with a high specific surface area and hierarchically porous structure. Ultrafine Ru NPs were successfully anchored on the hierarchal porous N-doped carbon nanospheres (HPNC) with high dispersion. The obtained Ru/HPNC catalyst exhibited excellent catalytic performance for LA hydrogenation to GVL under solvent-free conditions with outstanding reusability. In contrast, Ru NPs embedded in other supports (including activated carbon and carbon nanotubes) were observed to be less effective under the same reaction conditions. The superior catalytic performance of the Ru/HPNC catalyst is due to the hierarchically porous catalyst structure, and accessible ultrafine Ru active sites which can promote the activation of CO bonds and H2 absorption during the catalytic process. The reaction pathway of LA hydrogenation to GVL is clearly researched by theoretical calculations. Thus, the current work provides a facile strategy for the synthesis of highly dispersed ultrafine metal NP-based catalysts for an important biomass transformation.