Entropy Research Articles

A Record-High Cryogenic Magnetocaloric Effect Discovered in EuCl2 Compound.

Adiabatic demagnetization refrigeration (ADR) based on the magnetocaloric effect (MCE) is a promising technique to achieve cryogenic temperature. However, magnetic entropy change (ΔSM), the driving force of ADR, remains far below theoretical -ΔSM = nRln(2J + 1)/MW for most magnetic refrigerants. Here, we report giant MCE in orthorhombic EuCl2, where a ferromagnetic ground state with excellent single-ion behavior of Eu2+ and free spins has been demonstrated by combining ab initio calculations with Brillouin function analysis and magnetic measurements. Consequently, a record-high -ΔSM ∼ 74.6 J·kg-1·K-1 (1.8 K) at 5 T was experimentally achieved, approaching 96% of the theoretical limit (77.5 J·kg-1·K-1). At a lower field of 1 T, EuCl2 also achieves the highest-ever record of -ΔSM ∼ 36.8 J·kg-1·K-1. Further, direct quasi-adiabatic demagnetization measurements demonstrate that its large -ΔSM allows EuCl2 to maintain a long holding time at sub-Kelvin temperature (∼346 mK), surpassing all previously reported materials. These superior magnetocaloric performances position EuCl2 as an attractive cryogenic refrigerant.

A {Cr4Ln2} Complex with Exchange Coupled {Cr2} Units: Structural Description and Magnetic Study.

We have prepared and structurally characterized pivalate based {CrIII4LnIII2} complexes with Ln=Dy and Gd as well as the Y analogue, with the overall formula [CrIII4LnIII2(mdea)2(piv)10(OH)4], Ln= Gd, Dy and Y. We are reporting a detailed experimental magnetic properties study, including magnetization relaxation dynamics and calorimetric data, supported with quantum chemical calculations. The synthesis of the Y derivative, allowed to precisely identify the Cr(III)-Cr(III) exchange interaction magnitude which proved moderately strong and in agreement with known magneto-structural correlations. This result agrees with the observed double bridged {Cr2-mOH-mOR} units within the {Cr4Ln2} complexes.The Gd(III) complex magnetic properties can be properly described with the already established exchange coupled {Cr2} units, and a unique Gd(III)-Cr(III) exchange coupling parameter which proved anti-ferromagnetic in nature.The MCE characterization of this complexbased on magnetization and calorimetric data down to 2 K affords a moderate entropy change value, mainly affected by the strong Cr-Cr exchange interaction.The complex with Ln=Dy, showed SMM behaviour below 10 K under 0 DC applied field with negligible field dependence up to 3000 Oe and 10 kHz of AC field frequency. Two relaxation processes are clearly distinguished, with thermal barriers for an Orbach mechanism of ca. 20 cm-1 and 40 cm-1.

Influence of synthesis protocol on structure, magnetic and magnetocaloric properties of ErCrO3

In this study, we investigated the morphology, structure, magnetic, and magnetocaloric properties of ErCrO3 (ECO) nanoparticles synthesized through two distinct chemical routes: combustion and hydrothermal methods. X-ray diffraction analysis revealed a well-crystallized orthorhombic pbnm phase in both samples. The broader Raman peaks observed in the hydrothermal sample indicate a larger strain of 0.138%, compared to the combustion-derived sample. A significant reduction in the magnetic phase transition temperature was observed for ECO nanoparticles synthesized via the hydrothermal method (117 K) compared to those derived from combustion (∼130 K), which can be attributed to size-induced strain. The hydrothermal ECO samples exhibited a broader temperature span and lower entropy changes compared to the combustion-derived counterparts. Consequently, we observed an improved relative cooling power of 523 J K−1 and entropy change of −10.8 J kg−1 K−1 at a magnetic field of 50 kOe. These findings are promising for magnetic refrigeration applications. The ability to tailor magnetocaloric properties through straightforward synthesis methods underscores their significance in advancing potential applications.

Positive activation entropy of Bacillus circulans xylanase catalyzed ONPX2 hydrolysis: A mechanistic and engineering study

Transition state (TS) stabilization by enzymes greatly accelerates catalytic reactions. For some enzymes, the TS complex has entropy higher than enzyme substrate (ES) complex. But the origin of favorable entropy remains unclear. In this work, we studied the mechanism of Bacillus Circulans xylanase (BCX) 11 catalyzed o-nitrophenyl β-xylobioside (ONPX2) glycoside hydrolysis. The catalytic reaction exhibits a positive activation entropy, and an increase in ionic strength leads to a decrease in entropy without affecting the activation free energy, indicating that the entropy is predominantly influenced by electrostatic forces. Moreover, NMR measurements of electrostatic attractions within the active site demonstrate a positive entropy, aligning with molecular dynamics (MD) simulations showing that electrostatic interactions contribute to the entropic stabilization of the TS complex. These findings suggest that the positive entropy primarily originates from alterations in electrostatic interactions due to the formation of the oxocarbenium ion at C1 in the TS. Differences of electrostatic interactions in ES and TS modify hydrogen bonding of surrounding residues in the active site which causes their side chain dynamics and thus conformational entropy changes. Residues critical for the positive activation entropy are identified. A new BCX mutant with an increased activation entropy and catalytic activity is found.

Fe2O3/polypyrrole/peanut husk composite for the adsorptive removal of Basic Blue 41 from the aqueous medium: Kinetics, equilibrium modeling and thermodynamic studies

In this study, Basic Blue 41 (BB41) was adsorbed from an aqueous medium using a peanut husk (PH) functional composite with polypyrrole/Fe3O4. For the adsorption of BB41 dye, the effects of process variables including pH, sorbent dose, dye concentration, agitation time, and temperature were investigated. The magnetic composite showed the highest efficiency for the adsorbents at pH 7-10, 0.05 g adsorbent dose, 90 min contact time and 200 mg/L initial dye concentration at 27 °C. The qe was found up to 48 mg/g with percentage removal of up to 96% for BB41 dye for the composite. On the experimental data of BB41 dye, the Langmuir, Freundlich, Temkin, Harkin-Jura, and Dubinin-Radushkevich isotherms were applied. The BB41 adsorption data were also subjected to pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models. Thermodynamic factors, such as the change in enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°), were also calculated. The results show that the BB41 adsorption process is exothermic and spontaneous. Techniques such as FT-IR and scanning electron microscopy (SEM) were used to characterize the composite materials. This study demonstrated the promising adsorption potential of magnetic/polypyrrole/peanut husk composites. This class of adsorbent could be used to remediate wastewater that contains dyes.

Modeling Europium (II/III) ion solvation in the LiCl-KCl eutectic mixture with polarizable force fields

The solvation processes of Europium (II/III) ions within the molten salt eutectic mixture, 3LiCl-2KCl, are investigated over temperatures ranging from 673 K to 1173 K. New polarizable ion force fields are proposed to model Europium ions in a molten salt eutectic mixture with a goal of accurately capturing the underlying physics in the solutions. In contrast to rigid-ion models, the polarizable Drude model with an adjusted WBK (Wang-Buckingham) force field significantly improves predictions for diffusion coefficients, the average diffusion activation energy, and changes in excess ion chemical potential and partial molar entropy, producing good agreement with experimental measurements.

Unveiling the Structural, Electronic and Magnetic Properties of Gd4.5A0.5Si3O13 (A = K, Na, and Li) Oxides With Promising Potential for Low-Temperature Magnetic Cooling.

The growing demand for solid-state magnetic cooling, leveraging the magnetocaloric effect requires the discovery of high-performing magnetocaloric materials (MCMs). Herein, a family of Gd-containing MCMs is provided, specifically the Gd4.5A0.5Si3O13 (A = K, Na, and Li) oxides, which demonstratse exceptional low-temperature magnetocaloric performance. Through comprehensive experimental investigations and theoretical calculations on their structural, electronic, and magnetic properties, it is unequivocally confirmed that all of them crystallize in a hexagonal apatite-type structure (space group P63/m), exhibiting an antiferromagnetic semiconductor ground state with magnetic ordering temperatures below 1.8 K (typically ≈0.7 K for Gd4.5K0.5Si3O13). Furthermore, their remarkable maximum magnetic entropy change (-ΔSM max) values of 31.85 and 58.22 JkgK-1 for Gd4.5K0.5Si3O13; 25.31 and 55.01 JkgK-1 for Gd4.5Na0.5Si3O13; and 25.15 and 55.77 JkgK-1 for Gd4.5Li0.5Si3O13, under the magnetic field changes of 0-2 and 0-5 T, respectively, surpass those of prominent low-temperature MCMs, including the commercialized Gd3Ga5O12 (≈14.6 and 32.8 JkgK-1) paramagnetic salt. These findings in addition to their high environmental stability position these Gd4.5A0.5Si3O13 oxides as exceptionally promising for practical magnetic cooling applications.

Magnetocaloric effect in geometrically frustrated GdInO[formula omitted]

We have investigated the magnetic and magnetocaloric properties of geometrically frustrated rare-earth indium oxide, GdInO3, by magnetization and heat capacity measurements. It is found that the spin moments of Gd3+ ion undergo a paramagnetic to antiferromagnetic transition below 2 K. At low-magnetic fields, the dc magnetic susceptibility exhibits a clear deviation from the Curie–Weiss (CW) law below 150 K due to the strong magnetic frustration. However, with increasing field strength, the magnetic frustration weakens and the susceptibility data follow the expected CW behavior down to 2 K. The effective paramagnetic moment of Gd3+ ion calculated from the CW fit (∼8μB/Gd) is very close to the theoretical value for S=7/2. The maximum values of magnetic entropy change and adiabatic temperature change for a field change of 0–7 T are found to be ∼21 J kg−1 K−1 (∼155 mJ cm−3 K−1) and ∼15 K, respectively, while the refrigeration capacity is found to be ∼188 J kg−1 for μ0H = 7 T. The large values of magnetocaloric parameters along with negligible hysteresis loss suggest that GdInO3 could be considered as a potential candidate for magnetic refrigeration at low temperature.

Nb-doping in (Mn,Fe)2(P,Ge) giant magnetocaloric materials

The influence of Nb substitutions on the structure, magnetoelastic transition, and magnetocaloric properties is investigated in MnFe1−xNbxP0.76Ge0.24 (x = 0, 0.02, 0.04, 0.6) compounds. Powder XRD show that the compounds crystallize in the hexagonal Fe2P-type crystal structure (space group P6̄2 m) and contain minor amount of MnO impurity phase. At a low applied magnetic field (<1.6 T), the isothermal entropy change of the Nb-substituted MnFe0.98Nb0.02P0.76Ge0.24 sample is higher than that of the parent or more substituted samples, reaching a maximum of 14.0 J kg−1 K−1. Nb substitutions are found to efficiently reduce the thermal hysteresis in Ge-based Fe2P magnetocaloric materials; for instance, only 6 at. % of Nb for Fe substitution reduces the thermal hysteresis from 7.6 to 2.6 K while preserving giant magnetocaloric effect. Direct ΔTad measurements confirm the cyclic character of the giant magnetocaloric effect for x = 0.02.

Study on the mixed deposition rate and phase transition thermodynamic parameters of crude oil wax crystals and hydrates

Throughout the development of deepwater oil and gas fields, the occurrence of mixed deposition involving wax and hydrate is a prevalent phenomenon. To understand this process, researchers have explored the kinetics and thermodynamic behavior governing the co-deposition of wax and hydrates. It was observed that the Gibbs free energy change of hydrate increases with increasing pressure, while the entropy change experiences a decrease under heightened pressure conditions. The Gibbs free energy change and entropy change of wax crystal precipitation exhibit an increase with rising wax concentration. In a 100 mL sample of simulated crude oil containing 10 vol% moisture and 2.5 wt% wax, the rate of solid phase deposition measures 0.1126 cm3/min when the temperature drops from 61 °C to 2 °C. The results exhibit that the dispersion of wax crystals within the oil phase serves to inhibit aggregation phenomenon during hydrate formation and can be effectively used to inhibit hydrate deposition.

Study on polymer-containing oily sludge as a potential fuel by combustion thermochemistry

The environmental and resource issues posed by oil sludge have sparked a renewed interest in cleaner and more efficient oil production. The investigation on the combustion process of polymer-containing oily sludge (POS) is expected to open up new markets for POS as an alternative fuel. TGA was used to examine the combustion behaviour, kinetics, and thermodynamics of POS, and X-ray fluorescence (XRF) was used to measure the chemical composition of POS ash to predict ash fouling and slagging. Based on the TG-DTG curves, the mass loss of POS in combustion studies was split into four major areas. The combined calculation method of model-free methods, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS), was applied to determine the activation energies from stage 1 to stage 4, which were 47.89 kJ/mol, 66.09 kJ/mol, 190.55 kJ/mol, and 98.37 kJ/mol, respectively. A four-stage kinetic model (D4→D2→D3→R2) was established to describe the combustion process of POS. Compared to other conventional sludges, POS has a relatively low activation energy and is more susceptible to thermochemical transformations. The difference between the enthalpy change (ΔH) and activation energy (E) indicated that the reactions benefit the formation of the activated complex. Meanwhile, the change in entropy (ΔS) implied the thermodynamic disequilibrium in the 3rd stage of POS and completion of the thermal conversion at the end of the reaction. The change in Gibbs free energy (ΔG) increased in a stepwise manner and its lower average value reflected the greater reaction favourability of combustion for POS. The composition of POS ash was mainly metal oxides, with the slagging index, fouling index, and slagging viscosity index of 1.0, 9.1, and 32.0, respectively. POS ash has high fouling and slagging, with special attention in the combustion application.

Stochastic Entropy Production Associated with Quantum Measurement in a Framework of Markovian Quantum State Diffusion

The reduced density matrix that characterises the state of an open quantum system is a projection from the full density matrix of the quantum system and its environment, and there are many full density matrices consistent with a given reduced version. Without a specification of relevant details of the environment, the time evolution of a reduced density matrix is therefore typically unpredictable, even if the dynamics of the full density matrix are deterministic. With this in mind, we investigate a two-level open quantum system using a framework of quantum state diffusion. We consider the pseudorandom evolution of its reduced density matrix when subjected to an environment-driven process that performs a continuous quantum measurement of a system observable, invoking dynamics that asymptotically send the system to one of the relevant eigenstates. The unpredictability is characterised by a stochastic entropy production, the average of which corresponds to an increase in the subjective uncertainty of the quantum state adopted by the system and environment, given the underspecified dynamics. This differs from a change in von Neumann entropy, and can continue indefinitely as the system is guided towards an eigenstate. As one would expect, the simultaneous measurement of two non-commuting observables within the same framework does not send the system to an eigenstate. Instead, the probability density function describing the reduced density matrix of the system becomes stationary over a continuum of pure states, a situation characterised by zero further stochastic entropy production. Transitions between such stationary states, brought about by changes in the relative strengths of the two measurement processes, give rise to finite positive mean stochastic entropy production. The framework investigated can offer useful perspectives on both the dynamics and irreversible thermodynamics of measurement in quantum systems.

Thermodynamics and entropic inference of nanoscale magnetic structures in Gd

A bulk gadolinium (Gd) single crystal exhibits virtually zero remnant magnetization, a common trait among soft uniaxial ferromagnets. This characteristic is reflected in our magnetometry data showing virtually hysteresis free isothermal magnetization loops with large saturation magnetization. The absence of hysteresis allows to model the measured easy axis magnetization as a function of temperature and applied magnetic field, rather than a relation, which permits the application of Maxwell relations from equilibrium thermodynamics. Demagnetization effects broaden the isothermal first-order transition from negative to positive magnetization. By analyzing magnetization data within the coexistence regime, we deduce the isothermal entropy change and the field-induced heat capacity change. Comparing the numerically inferred heat capacity with relaxation calorimetric data confirms the applicability of the Maxwell relation. Analysis of the entropy in the mixed phase region suggests the presence of hitherto unresolved nanoscale magnetic structures in the demagnetized state of Gd. To support this prediction, Monte Carlo simulations of a 3D Ising model with dipolar interactions are performed. Analyzing the cluster size statistics and magnetization from the model provides strong qualitative support of our analytic approach.

Stability of the first-order character of phase transition in HoCo2

HoCo2 exhibits a giant magnetocaloric (MC) effect at its first-order magnetostructural phase transition around 77 K, and understanding the thermodynamic nature of this transition in response to external magnetic fields is crucial for its MC applications. In this study, we present a comprehensive investigation of specific heat and magnetization measurements of HoCo2 under varying magnetic fields. The specific heat measurements qualitatively indicate a transformation from first- to second-order behavior of this phase transition at higher magnetic fields. However, analysis of the power-law dependence of the magnetic entropy change (ΔSM∝Hn) and the breakdown of universal behavior in the temperature dependence of ΔSM suggest that the first-order nature remains intact, even up to 7 T. This stability of the first-order nature is further manifested through the distinctive non-linear behavior of modified Arrott plots, with a negative slope in the 6–7 T range.

Thermal Conversion of Coal Bottom Ash and Its Recovery Potential for High-Value Products Generation: Kinetic and Thermodynamic Analysis with Adiabatic TD24 Predictions

Thermal decomposition (pyrolysis) of coal bottom ash (collected after lignite combustion in coal-fired power plant TEKO-B, Republic of Serbia) was investigated, using the simultaneous TG-DTG techniques in an inert atmosphere, at various heating rates. By using the XRD technique, it was found that the sample (CBA-TB) contains a large amount of anorthite, muscovite, and silica, as well as periclase and hematite, but in a smaller amount. Using a model-free kinetic approach, the complex nature of the process was successfully resolved. Thermodynamic analysis showed that the sample is characterized by dissociation reactions, which are endothermic with positive activation entropy changes, where spontaneity is achieved at high reaction temperatures. The model-based method showed the existence of a complex reaction scheme that includes two consecutive reaction steps and one single-step reaction, described by a variety of reaction models as nucleation/growth phase boundary-controlled, the second/n-th order chemical, and autocatalytic mechanisms. It was established that an anorthite I1 phase breakdown reaction into the incongruent melting product (CaO·Al2O3·2SiO2) represents the rate-controlling step. Autocatalytic behavior is reflected through chromium-incorporated SiO2 catalyst reaction, which leads to the formation of chromium(II) oxo-species. These catalytic centers are important in ethylene polymerization for converting light olefin gases into hydrocarbons. Adiabatic TD24 prediction simulations of the process were also carried out. Based on safety analysis through validated kinetic parameters, it was concluded that the tested sample exhibits high thermal stability. Applied thermal treatment was successful in promoting positive changes in the physicochemical characteristics of starting material, enabling beneficial end-use of final products and reduction of potential environmental risks.

Ibuprofen photodegradation promoted by ZnO and TiO2-P25 nanoparticles: A comprehensive kinetic, reaction mechanisms, and thermodynamic investigation

Photocatalytic activity, reaction kinetics, modeling, and thermodynamics of commercial TiO2-P25 and ZnO nanoparticles (NPs) for ibuprofen (IBU) photodegradation were investigated. Photodegradation experiments were performed in a batch reactor under UV irradiation. The photodegradation performances of TiO2-P25 and ZnO NPs were further studied and modeled under different operation conditions, by varying the reaction temperature, catalyst bulk density, and the initial concentration of the IBU solution. The descriptive kinetic models for the experimental data were tested, through the estimated kinetic parameters, together with the statistical information, revealing that the reaction rate in the case of TiO2-P25 is of first order while the ZnO NPs follow second-order kinetics with respect to IBU. The photodegradation mechanisms for both TiO2-P25 and ZnO NPs were determined to be Langmuir-Hinshelwood and Eley-Rideal, respectively. Thermodynamic parameters were assessed, particularly, changes in Gibbs free energy, enthalpy, and entropy indicating the efficient photodegradation performance of these NPs.

Large room-temperature elastocaloric effect and enhanced specific adiabatic temperature change of Ni–Mn-based shape memory microwire

Continuous miniaturization of electronic components puts higher demands on the heat dissipation of the micro-systems, which requires environmental friendliness, good heat exchange capability, and high-performance micro-refrigeration materials. Here, we developed a Ni–Mn–Fe–In microwire fabricated by the Taylor–Ulitovsky method, showing ⟨001⟩A orientation close to the axial direction of microwire. Due to the large volume change ΔV/V (−1.24%), the large entropy change ΔStr of 43.6 J kg−1 K−1 was achieved in the microwire. Owing to the low driving force of the microwire with a single crystalline of ⟨001⟩A orientation close to the axial direction of microwire, large adiabatic temperature change of −5.7 K was achieved at room temperature after removing a low stress of 120 MPa. Thus, high specific adiabatic temperature change of 47.5 K/GPa was obtained in the microwire, which is the highest value among all the reported low-dimension elastocaloric materials, including thin films/foils, microwires/wires, and ribbons. The outstanding comprehensive properties give this microwire a great application potential in miniaturization and compactness of refrigeration devices.

Giant Inverse Barocaloric Effect of Ferroelectric Salts Driven by Negative Thermal Expansion

AbstractRefrigeration technologies based on the barocaloric effect have garnered significant attention, while their potential applications are limited by the poor performance of current materials. Here it is proposed that ferroelectric ionic salts with covalent‐like bondings like LiI may become ideal candidates. The pressure‐induced phase transition between two phases with distinct densities and entropies leads to tremendous negative thermal expansion (with volume reduced by 13%) and inverse barocaloric effect, which are facilitated by the low transition barriers due to the long‐range Coulomb interaction. Using ab initio‐based training database, we trained the machine learning potential of LiI based on a deep neutral network‐based mode, and this simulations of its barocaloric effect reveal a high entropy change and thermal conductivity, and in particular, the estimated adiabatic temperature change, pressure sensitivity and relative cooling power are all unprecedented. This prediction provides a high‐performance barocaloric mechanism for practical applications and also expands the scope of barocaloric materials to simple and facile binary salts.

Excess properties, intermolecular interaction, and CO2 capture performance of diethylene glycol monomethyl ether + ethylenediamine binary mixed solutions

In this work, the density (ρ) and viscosity (η) values of diethylene glycol monomethyl ether (DEGME) (1) + ethylenediamine (EDA) (2) binary mixed solutions were experimentally measured over the temperature span of 298.15–318.15 K and at a constant pressure of 100.5 kPa. To delve into the physicochemical properties of the binary mixed solutions, the excess properties, including excess molar volume, viscosity deviation, and excess molar activation Gibbs free energy, and thermodynamic values, including activation Gibbs free energy, enthalpy change, entropy change, and activation energy, were systemically calculated. Furthermore, the relationship between mole fraction and temperature was modeled using the Jouyban-Acree (J-A) model and a least squares method. Additionally, the three-body McAllister, the four-body McAllister, the Eyring-Margules, and the Heric viscosity models were employed to establish a relationship between viscosity and mole fraction. The relationship between viscosity and temperature was determined utilizing the Arrhenius equation, and the Redlich-Kister (R-K) polynomial was applied to fit the excess molar volume, viscosity deviation, and excess molar activation Gibbs free energy values of the binary mixed solutions. To further validate the intermolecular interactions within the binary mixed solutions, Raman, UV, and 1H NMR spectroscopic analyses, and density-functional theory (DFT) calculations were also conducted. These comprehensive analyses collectively confirmed the presence of significant intermolecular hydrogen bonds (IHBs) between the DEGME and EDA molecules, which are characterized as the –OH⋯NH2– interaction. Ultimately, the CO2 absorption capacity of the binary mixed solutions was examined, revealing that diethylene glycol monomethyl ether (DEGME) (1) + ethylenediamine (EDA) (2) binary mixed solutions owned superior CO2 absorption efficiency, thus offering a promising approach for CO2 capture.

Effect of La–Ni@3DG catalyst concentration on the hydrogen storage properties of MgH2

This research paper explores the influence of varying the quantity of La–Ni@3DG catalyst on the hydrogen storage capabilities of MgH2. La–Ni@3DG catalyst was prepared using lanthanum chloride heptahydrate and nickel chloride hexahydrate as raw materials combined with three-dimensional graphene, then mixed with MgH2 via ball milling to prepare MgH2 + x wt.% La–Ni@3DG (x = 0, 3, 5, 7) composite alloy. X-ray diffraction analysis showed that the composite alloy was mainly composed of the MgH2 phase, with the presence of Mg and (La, Ni) phases detected. With increased La–Ni@3DG addition, the broadening of the MgH2 diffraction peak significantly improved, indicating the catalyst promoted alloy phase structure uniformity and crystallinity. The composite alloy forms new phases such as LaH3, LaNi3H6, and Mg2NiH4 during hydrogen absorption. These phases cooperate with in-situ formed LaH3 and Mg2Ni to significantly improve the reversible hydrogen absorption and desorption properties of MgH2. Adding La–Ni@3DG catalyst has a significant positive effect on the hydrogen absorption and desorption of MgH2, leading to a considerable improvement. At 553 K, the composite alloy reaches hydrogen absorption equilibrium faster than pure MgH2, and the temperature for hydrogen absorption is significantly reduced to 373 K. The dehydrogenation performance is also improved, with 5 wt.% La–Ni@3DG is showing the best dehydrogenation performance at 553 K. The initial dehydrogenation temperature commences at approximately 505 K, while the dehydrogenation activation energy attains its minimum value: a remarkably low 109.91 kJ/mol H2. Additionally, the addition of catalyst reduces the pressure of the hydrogen absorption and desorption platform, effectively reducing the hysteresis effect during hydrogen absorption and desorption when the catalyst content is 5 wt.%, the enthalpy change and entropy change of the composite alloy reach a minimum, −70.45 kJ/mol H2 and 74.38 kJ/mol H2 (hydrogen absorption), −101.93 J/K/mol H2 and 103.68 J/K/mol H2 (hydrogen desorption), respectively.