Hierarchical porous graphene-based carbons prepared by carbon dioxide activation and their gas adsorption properties

Hierarchical porous graphene-based carbons (HPGCs) have been prepared by a simple carbon dioxide activation of graphite oxide. The effects of activation temperature on the structural and textural properties as well as gas adsorption capacities of the resultant carbons have been investigated. The HPGCs showed hierarchically micro-meso-macroporous structures, high specific surface areas of up to 532 m² g⁻¹, and large pore volumes of up to 1.67 cm³ g⁻¹. Moreover, the HPGC materials were demonstrated to be efficient for CO₂ and H₂ adsorption. The HPGC-850, which was obtained after two hours of activation at 850 °C, exhibited the highest adsorption capacities of 7.74 wt% (1.76 mmol g⁻¹) at 273 K and 1 bar for CO₂ and of 0.75 wt% (3.76 mmol g⁻¹) at 77 K and 1 bar for H₂.     

Nitrogen doped mesoporous carbon supported Pt electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells

Nitrogen doped mesoporous carbons are employed as supports for efficient electrocatalysts for oxygen reduction reaction. Heteroatom doped carbons favour the adsorption and reduction of molecular oxygen on Pt sites. In the present work, nitrogen doped mesoporous carbons (NMCs) with variable nitrogen content were synthesized via colloidal silica assisted sol-gel process with Ludox-AS40 (40 wt% SiO₂) as hard template using melamine and phenol as nitrogen and carbon precursors, respectively. The NMC were used as supports to prepare Pt/NMC electrocatalysts. The physicochemical properties of these materials were studied by SEM, TEM, XRD, BET, TGA, Raman, XPS and FTIR. The surface areas of 11 wt% (NMC-1) and 6 wt% (NMC-2) nitrogen doped mesoporous carbons are 609 m² g^?1 and 736 m² g^?1, respectively. The estimated electrochemical surface areas for Pt/NMC-1 and Pt/NMC-2 are 73 m² g^?1 and 59 m² g^?1, respectively. It is found that Pt/NMC-1 has higher ORR activity with higher limiting current and 44 mV positive onset potential shift compared to Pt/NMC-2. Further, the fuel cell assembled with Pt/NMC-1 as cathode catalyst delivered 1.8 times higher power density than Pt/NMC-2. It is proposed that higher nitrogen content and large pyridinic nitrogen sites present in NMC-1 support are responsible for higher ORR activity of Pt/NMC-1 and high power density of the fuel cell using Pt/NMC-1 cathode electrocatalyst. The carbon support material with high pyridinic content promotes the Pt dispersion with particle size less than 2 nm.     

Preparation of activated biomass carbon from pine sawdust for supercapacitor and CO2 capture

Biomass based carbon has captured more and more attention because it is environmentally friendly and has properties of low cost and ideal sustainability. In this study, three kinds of activated biomass carbons (ie, ABC-700, ABC-800 and ABC-900) were first carbonized through pine sawdust pyrolysis and then activated using KOH under three different activation temperatures (ie, 700°C, 800°C and 900°C). The structure properties of the prepared activated biomass carbons were characterized by N₂-adsorption/desorption, SEM, TEM, XRD, Raman, XPS, TG and ultimate analysis. To clarify the activation mechanism, the gas products produced during KOH activation process were measured online with an ETG gas analyzer. The performance of the activated biomass carbons derived from pine sawdust for supercapacitor and CO₂ capture was then evaluated. The predominant gas products during the activation process are H₂ and CO. It indicates that the porous structure was created by using an enhanced etching reaction between carbon atoms and KOH. An increment of the activation temperature from 700 to 900°C results in the increase of surface area (from 1728.66 to 2330.89 m²/g) and total pore volume (from 0.671 to 1.914 cm³/g). Among the three samples, ABC-900 exhibits the maximal specific capacitance of 175.6 F·g⁻¹ and high energy density of 24.39 Wh·kg⁻¹ at the 0.5 A·g⁻¹. And the ABC-700 shows the maximal CO₂ capture capacity of 4.21 mmol/g and high selectivity of CO₂ over N₂ at 298 K and 1 bar. In addition, ABC-700 also has excellent stability and reproducibility after 15 times adsorption-desorption cycles. The unexceptionable electrochemical performance and adsorption capacity of the biomass-carbons show its broad application prospects in the field of supercapacitors and CO₂ capture.     

Rice straw-based activated carbons doped with SiC for enhanced hydrogen adsorption

Activated carbons (ACs) based on rice straw (RS) were synthesised using potassium carbonate as activating agent at three different K₂CO₃/RS weight ratios. Morphological, chemical, structural as well as textural characterisations were carried out in order to establish relationships between the physicochemical properties of the materials and their hydrogen adsorption capacities. The ACs contained potassium and silicon as the main impurities. Si was identified by XRD in both phases of silicon dioxide and silicon carbide. The presence of SiC was particularly surprising due to the rather low activation temperature, much lower than what is usually required for SiC synthesis. ACs exhibited well-developed surface areas (approximatively 2000–2100 m² g^?1) and high micropore volumes, making them suitable for hydrogen storage applications. RS-based ACs showed higher hydrogen storage capacities than those previously obtained with KOH-activated sucrose. The latter exhibited hydrogen uptakes (excess, 10 MPa, 298 K) up to 0.55 wt. %, whereas 0.65 wt. % was measured for RS-based ACs in the same conditions. The higher hydrogen capacities and isosteric heats of adsorption found here were attributed to the presence of SiC.     

Lignin‐derived heteroatom‐doped porous carbons for supercapacitor and CO2 capture applications

The present study reports the economic and sustainable syntheses of functional porous carbons for supercapacitor and CO₂ capture applications. Lignin, a byproduct of pulp and paper industry, was successfully converted into a series of heteroatom‐doped porous carbons (LHPCs) through a hydrothermal carbonization followed by a chemical activating treatment. The prepared carbons include in the range of 2.5 to 5.6 wt% nitrogen and 54 wt% oxygen in its structure. All the prepared carbons exhibit micro‐ and mesoporous structures with a high surface area in the range of 1788 to 2957 m² g^?1. As‐prepared LHPCs as an active electrode material and CO₂ adsorbents were investigated for supercapacitor and CO₂ capture applications. Lignin‐derived heteroatom‐doped porous carbon 850 shows an outstanding gravimetric specific capacitance of 372 F g^?1 and excellent cyclic stability over 30,000 cycles in 1 M KOH. Lignin‐derived heteroatom‐doped porous carbon 700 displays a remarkable CO₂ capture capacity of up to 4.8 mmol g^?1 (1 bar and 298 K). This study illustrates the effective transformation of a sustainable waste product into a highly functional carbon material for energy storage and CO₂ separation applications.     

La-promoted Ni/Mg-Al catalysts with highly enhanced low-temperature CO2 methanation performance

In this paper, we investigated the effect of adding lanthanum on the structure and low-temperature activity of the Ni/Mg-Al catalyst for CO₂ methanation. A series of La-doped Ni/Mg-Al catalysts with different La loadings were synthesized by urea hydrolysis method. The results showed that La-promoted NiLax (x = 2, 5 and 8 wt%) catalysts exhibited higher low-temperature activity than the Ni catalyst without La added. In particular, the NiLa5 catalyst performed the best, getting as high as 61% CO₂ conversion and nearly 100% CH₄ selectivity at 250 °C, 0.1 MPa, and a WHSV of 45,000 mL g^?1 h^?1. Characterization results revealed that La effectively increased Ni dispersion and decreased Ni particle size. In addition, La could significantly increase the amount of moderate basic sites, which contributed to enhanced CO₂ adsorption capacity. Compared with coprecipitation method, urea hydrolysis method was proved to be a more efficient approach for the Ni-based catalyst preparation, getting the Ni-based catalyst with higher Ni dispersion, larger CO₂ adsorption capacity and thereby better catalytic performance.     

Synthesis and characterization of KOH/boron modified activated carbons from coal and their hydrogen sorption characteristics

Activated carbons from bituminous coal taken from the area of Zonguldak Kilimli region in Turkey were synthesized by chemical activation using a mixed combination of KOH and as a boron source borax decahydrate. The modification process consists of chemical activation of the demineralized coal with KOH (KOH/coal:4/1) and various concentrations of borax decahydrate solutions (0.025–0.1 M). Textural properties such as surface area and pore structure were studied by volumetric methods using N₂ adsorption data at 77.4 K (P/P₀ = 0–1). The samples obtained have high microporosity, in the form of irregular structures. The EDAX spectra indicate that Boron heteroatoms are attached to surface of AC41, and as BDH concentration increases from 0.025 M to 0.1 M, higher atomic percent of boron is accumulated at the surfaces. AC41 exhibits amorphous structures, whereas BDH modified AC41 consists of predominantly amorphous structure and disordered graphitic carbon. Among the synthesized boron modified samples, the highest surface area, total pore volume and average pore diameters were found for the 0.025 M_BDH-AC41 sample. As the BDH concentration increases, the volume of N₂ adsorbed decreases. Surface area of CC and AC41 samples were 52.62 and 2228 m²/g, respectively, whereas surface area of the boron modified samples were found in the range of 2190–2704 m²/g. Hydrogen sorption capacities of the KOH/boron modified samples were found in the range between 2.08 and 3.74% wt. Hydrogen sorption capacity of AC41 obtained was 4.11% wt. Increasing boron concentration resulted in the decrease of hydrogen sorption capacities. Boron modified activated carbons were prepared successfully from coal samples by chemical activation using a mixed combination of KOH and BDH.     

Novel sustainable nitrogen,iodine-dual-doped hierarchical porous activated carbon as a superior host material for high performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries exhibit great potential for next-generation high energy density energy storage. However, the insulativity of sulfur and the “shuttle effect” of polysulfides result in low utilization efficiency of active sulfur, fast capacity decay and inferior cycling stability, which pose the key challenge to their practical applications. Herein, a N, I-dual-doped hierarchical porous activated carbon (NIWFC) is successfully prepared for advanced Li-S batteries by the simple one-pot pyrolysis and hydrothermal processes. The obtained NIWFC owns interconnected porous framework with desirable specific surface area (2088.56 m² g^?1) and large volume space (1.106 cm³ g^?1), which can accommodate high content of active sulfur and immobilize polysulfides through physical confinement. Moreover, the existence of N and I heteroatoms could effectively strengthen the chemical adsorption to polysulfides and create more active sites to enhance sulfur utilization. Attributed to these merits, impregnating sulfur into NIWFC (NIWFC/S) as cathode of Li-S batteries achieves a high initial discharge capacity of 1284.1 mAh g^?1 at 0.1 C (remaining at 916.7 mAh g^?1 after 100 cycles) and the outstanding cycling stability with a low capacity fading rate of 0.061% per cycle over 350 cycles at 1.0 C. This work provides a facile and cost-effective strategy to design a novel sustainable N, I-dual-doped porous carbon for high performance Li-S batteries and various energy storage fields.     

Enhanced methane storage of chemically and physically activated carbide-derived carbon

Carbide-derived carbons (CDCs) produced by chlorination of carbides offer great potential for precise pore size control at the atomic level, making them attractive candidates for energy storage media. CDCs activated with CO₂ or KOH possess distinct improvements in porosity, displaying specific surface areas above 3000 m² g⁻¹ and pore volumes above 1.3 cm³ g⁻¹. These correspond to gravimetric methane uptake of 16 wt% at 35 bar and 25 °C, close to the currently best reported material PCN-14, a metal-organic framework (MOF), at 35 bar and 17 °C or KOH activated anthracite at 35 bar and 25 °C. The best excess gravimetric methane uptake is obtained with a TiC-derived CDC activated with CO₂ at 975 °C for 2 h, namely a very large surface area of 3360 m² g⁻¹ resulting in 18.5 wt% at 25 °C and 60 bar. To obtain realistic volumetric methane capacity, the packing density of completely dried CDC was measured, from which we obtain excess capacity of 145 v(STP) v⁻¹ from CDC activated with CO₂ at 875 °C for 8 h, 81% of the DOE target (180 v(STP) v⁻¹) at 35 bar and 25 °C. From small-angle X-ray scattering (SAXS) measurements, pore radii of gyration (R_g) between 0.5 nm and 1 nm are determined. Temperature-dependent methane isotherms show that the isosteric heat of adsorption reaches 24 kJ mol⁻¹ at the initial stage of low loading.     

Conversion of hydrogen/carbon dioxide into formic acid and methanol over Cu/CuCr2O4 catalyst

Cu/CuCr₂O₄ catalysts were prepared by impregnation method at various calcination temperatures (300, 400, and 500 °C) and then reduced in H₂ stream. The aggregated particles and decreasing surface area/pore volumes of the deactivated catalysts during HCOOH and CH₃OH formations were also observed. Particularly, the EXAFS data showed that first shells of Cu atoms transforms from Cu–O to Cu–Cu after catalytic reactions, their bond distances and coordination numbers are quite different, respectively. It revealed that metallic Cu atoms are one of the important active species over catalyst surface at different reaction temperatures having many unoccupied binding sites for HCOOH and CH₃OH formations. Additionally, the optimal calcination temperature for Cu/CuCr₂O₄ catalysts was demonstrated at 400 °C that attributed to its strongest acidity and basicity. The catalytic reactions in the duration of HCOOH and CH₃OH preparation were proposed that were composed of HCOOH formation, CH₃OH formation, and CH₃OH decomposition happening at CuCr₂O₄, Cu, and CuO active sites, respectively. The highest CO₂ conversion (14.6%), HCOOH selectivity/yield (87.8/12.8%), and TON/TOF values (4.19/0.84) were obtained at 140 °C and 30 bar in 5 h, respectively. Optimal rate constant (2.57 × 10^?2 min^?1) and activation energy (16.24 kJ mol^?1) of HCOOH formation were evaluated by pseudo first-order model and Arrhenius equation, respectively.     

CO2 methanation over Ni and Rh based catalysts: Process optimization at moderate temperature

H₂ was produced from aluminum/water reaction and reacted with CO₂ over Ni and Rh based catalysts to optimize the process conditions for CO₂ methanation at moderate temperature. Monometallic catalysts were prepared by incorporating Ni and Rh using nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and rhodium(III) chloride trihydrate (RhCl₃·3H₂O)as a precursor chemical. The preliminary study of the catalysts revealed higher activity and CH₄ selectivity for Rh based catalyst compared to that of Ni based catalyst. Further, Rh based catalyst was investigated using response surface methodology (RSM) involving central composite design. The quadratic model was employed to correlate the effects of variable parameters including methanation temperature, %humidity, and catalyst weight with the %CO₂ conversion, %CH₄ selectivity, and CH₄ production capacity. Analysis of variance revealed that methanation temperature and humidity play an important role in CO₂ methanation. Higher response values of CO₂ conversion (54.4%), CH₄ selectivity (73.5%) and CH₄ production capacity (8.4 μmol g^?1 min^?1) were noted at optimum conditions of 206.7°C of methanation temperature, 12.5% humidity and 100 mg of the catalyst. The results demonstrated the ability of Rh catalyst supported on palm shell activated carbon (PSAC) for CO₂ methanation at low temperature and atmospheric pressure.     

Investigation of adsorption properties of geological materials for CO2 storage

The assessment for realistic CO₂‐adsorption capacities of different rocks is important for understanding the processes associated with CO₂ storage. This paper investigates the adsorption characteristics of rocks for CO₂ (limestone, sandstone, marl, claystone, clay, siltstone and metamorphic rock) by using a gravimetric method. The measurements were performed at 21°C with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21°C. The highest amount of in situ CO₂ contents in measured samples was 21.4 kg/t. The CO₂‐adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO₂ into rocks may play an important role in storing CO₂ in subsurface rock. Copyright © 2012 John Wiley & Sons, Ltd.     

Methanation of carbon dioxide over Ni/CeO2 catalysts: Effects of support CeO2 structure

The CeO₂, which were prepared by hard-template method, soft-template method, and precipitation method, were used as support to prepare Ni/CeO₂ catalysts (named as NCT, NCS, and NCP catalysts, respectively). The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). Hydrogen temperature-programmed reduction (H₂-TPR) was also used to study the reducibility of the support nickel precursors. Moreover, CO₂ catalytic hydrogenation methanation was used to investigate the catalytic properties of the prepared NCT, NCS, and NCP catalysts. H₂-TPR and XRD results showed that the NiO can be reduced by H₂ to produce metal Ni species, and the surface oxygen species existing on the surface of the support CeO₂ can also be reduced by H₂ to form surface oxygen vacancies. Low-angle XRD, TEM, and BET results indicated that the NCT and NCS catalysts had developed mesoporous structure and high specific surface area of 104.7 m² g^?1 and 53.6 m² g^?1, respectively. The NCT catalyst had the highest CO₂ methanation activity among the studied NCT, NCS, and NCP catalysts. The CO₂ conversion and CH₄ selectivity of the NCT catalyst can reach 91.1% and 100% at 360 °C and atmospheric pressure. The NCP catalyst, which had low specific surface area and low porosity, performed less CO₂ conversion and higher CH₄ selectivity than the NCT and NCS catalysts till 400 °C.     

CO2 methanation over ordered mesoporous NiRu-doped CaO-Al2O3 nanocomposites with enhanced catalytic performance

The ordered mesoporous NiRu-doped CaO-Al₂O₃ nanocomposites were synthesized via a facile evaporation-induced self-assembly method for CO₂ methanation. Metallic Ni and Ru species retained the single-component heterostructure rather than NiRu alloy over the 600 °C-reduced catalysts. Owing to the synergistic effect of bimetallic Ni–Ru as well as the improved H₂ and CO₂ chemisorption capacities after the addition of Ru and CaO promoters, the ordered mesoporous 10N1R2C-OMA catalyst exhibited enhanced catalytic activity and selectivity, which achieved the maximum CO₂ conversion of 83.8% and CH₄ selectivity of 100% at 380 °C, 0.1 MPa, 30000 mL g^?1 h^?1. In a 550 °C-109 h-lifetime test, the ordered mesoporous 10N1R2C-OMA catalyst showed high stability and superior anti-sintering property due to the confinement effect of the ordered mesostructure.     

Nitrogen and oxygen dual-doped porous carbons prepared from pea protein as electrode materials for high performance supercapacitors

Porous carbons as electrode materials are highly desired for use in energy storage/conversion devices. Herein, the development of a series of highly porous nitrogen and oxygen co-doped carbons by using pea protein (PP) as a cost-effective, sustainable and nitrogen-rich precursor is reported. Pea protein derived carbons (PPDCs) have been prepared by applying a straightforward two-step synthetic route including pyrolysis and KOH-chemical activation. Potassium hydroxide has been employed to generate porosity and introduce oxygen functionalities into the framework of carbon. The heteroatoms doping content and porosity parameters have been tuned by varying the synthesis temperature and activator to precursor ratio. The carbon obtained with optimal synthetic parameters (T = 800 °C and KOH/Precursor = 4) featured the highest surface area, the maximal pore volume and N-/O doping level of 3500 m² g^?1, 1.76 cm³ g^?1, and 2.5-/17.9 at%, respectively. PPDC-4-800 as supercapacitor presented a very high specific capacitance (413 F g^?1 at 1.0 A g^?1 in 1 M KOH), remarkable cycling stability (92% retention after 20000 cycles) and outstanding rate capability (210 F g^?1 at 30 A g^?1). The cooperative effects of the well-developed porous architecture and surface modification of PPDCs resulted in enhanced electrochemical performances, suggesting their potential application for energy storage devices.     

Porous structure and morphology of granular chars from flash and conventional pyrolysis of grape seeds

This work studies the influence of the operating conditions used in the pyrolysis of grape seeds on the morphology and textural properties of the chars resulting. Flash and conventional (283 K min⁻¹ heating rate) pyrolysis have been used within a wide range of temperature (300–1000 °C). The effect of a pretreatment for oil extraction has also been studied. The porous structure of the chars was characterized by adsorption of N₂ at 77 K, Ar at 77 K and 87 K, and CO₂ at 273 K and mercury intrusion porosimetry. The morphology was analyzed by scanning electron microscopy. All the materials prepared revealed an essentially microporous structure, with a poor or even negligible contribution of mesopores. Increasing pyrolysis temperature led to higher specific surface areas and lower pore size. The highest specific surface area values occurred within 700–800 °C, reaching up to 500 m² g⁻¹ with pore sizes in the 0.4–1.1 nm range. No significant morphological changes were observed upon carbonization so that the resulting chars were granular materials of similar size than the starting grape seeds. The hollow core structure of the chars, with most of the material allocated at the periphery of the granules can help to overcome the mass transfer limitations of most common (solid or massive) granular activated carbons. The chars showed a good mechanical strength during attrition tests. These chars can be potential candidates for the preparation of granular carbons molecular sieve or activated carbons raw materials.     

The synthesized nickel-doped multi-walled carbon nanotubes for hydrogen storage under moderate pressures

Hydrogen adsorption capacity of Multiwalled carbon nanotubes (MWCNTs) decorated with Nickel (Ni) nanoparticles has been presented at room temperature and under moderate pressures of 4–20 bar. The functionalization of carbon nanotubes was carried by H₂SO₄-HNO₃ reducing agents and the Ni supported MWCNTs (Ni-MWCNTs) were prepared by wet chemical method. The structure and morphology characterization of samples were performed by XRD, TEM, EDX and SEM analyses. These nanotubes then subjected to hydrogenation step by using Sievert's-like apparatus. The hydrogenation of the Ni-MWCNTs was performed at 298 K and moderate hydrogen pressures of 4–20 bar. The obtained results show that there is a correlation between hydrogen storage capacity and hydrogen pressure that; as the pressure was increased, hydrogen uptake capacity enhanced due to physisorption. In addition, maximum hydrogen storage capacity of Ni-MWCNTs was found to be 0.298 wt % at room temperature and under pressure of 20 bar.     

Prediction of CO2 adsorption on different activated carbons by hybrid group method of data-handling networks and LSSVM

CO₂ is a ubiquitous species that has received much attention recently. The adsorption of CO₂ by means of activated carbons is a well-tried technology that can be used on a large scale. Improvements of the prediction models with more accurate results and lower error are necessary for future development of the projects and the economic dispatch sector. The least square support vector machine, a relatively unexplored neural network known as group method of data handling (GMDH), were implemented to forecast the CO₂ adsorption on different activated carbons. This work aims to provide new methods to predict the adsorption equilibrium of pure CO₂ on a set of commercial activated carbons and to express it regarding textural properties such as Brunauer–Emmett–Teller (BET) surface area, total pore volume, and micropore volume. Results indicated that the utilized models are very accurate in predicting CO₂ adsorption on different activated carbons. Comparison of the outcomes of the two models shows that the GMDH model is more accurate with R² and mean squared error values of 0.8915 and 0.0001425, respectively.     

A study on optimal pore range for high pressure hydrogen storage behaviors by porous hard carbon materials prepared from a polymeric precursor

In this study, activated polymer-based hard carbons were prepared using various steam activation conditions in order to enhance their hydrogen storage ability. The structural characteristics of the activated carbons were observed by X-ray diffraction and Raman spectroscopy. The N₂ adsorption isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller, Barrett-Joyner-Halenda and non-local density functional theory equations. The hydrogen storage behaviours of the activated carbons at 298 K and 10 MPa were studied using a Pressure-Composition-Temperature apparatus. From the results, specific surface areas and total pore volume of the activated carbons were determined to be 1680–2320 m²/g and 0.78–1.39 cm³/g, respectively. It was also observed that various pore size distributions were found to be dependent on the functions of activation time. In the observed result, the hydrogen adsorption of APHS-9-4 increased about 30% more than that of as-prepared hard carbon. This indicates that hydrogen storage capacity could be a function not only of specific surface area or total pore volume, but also of micropore volume fraction in the range of 0.63–0.78 nm of adsorbents.     

Enhanced hydrogen storage performance of three-dimensional hierarchical porous graphene with nickel nanoparticles

Three-dimensional hierarchical porous graphene with nickel nanoparticles (3DHPG-Ni) was synthesized through electrostatic assembly method with the assistance of poly (methyl methacrylate) (PMMA) template and subsequent removal of PMMA template by calcination. The morphology, microstructure and hydrogen adsorption properties of 3DHPG-Ni nanocomposites were examined in detail. The obtained 3DHPG-Ni nanocomposite exhibited hierarchical porous structure composed of macro-, meso- and micropores, high specific surface area (925 m² g^?1), large pore volume (0.58 cm³ g^?1) and excellent hydrogen storage capacity. Under the pressure of 5 bar, 3DHPG-Ni nanocomposite showed a maximum hydrogen capacity of 4.22 wt% and 1.95 wt% at 77 K and 298 K, respectively, demonstrating that the as-prepared 3DHPG-Ni nanocomposite was supposed to be a promising material with outstanding properties for practical applications in the field of hydrogen storage. The three-dimensional hierarchical porous structure, evenly distributed Ni nanoparticles and hydrogen spillover effect were responsible for the enhanced hydrogen storage capacities.