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Membrane‐based gas separation offers notable energy efficiency benefits for hydrogen purification, yet it is often hindered by the inherent trade‐off between permeability and selectivity. To address this challenge, a novel mixed matrix membrane (MMM) design is presented to boost H2 separation performance via continuous hydrogen spillover mechanisms for the first time. The MMM incorporates a palladium‐functionalized ZIF‐67 gel (Pd@ZIF‐67 gel) network into a polymer of intrinsic microporosity (PIM‐1) matrix. The ZIF‐67 gel network serves as a uniform dispersion medium for palladium nanoparticles (Pd NPs), thereby generating a multitude of active sites. These exposed sites, in conjunction with the microporous structure of ZIF‐67, facilitate hydrogen dissociation and establish a continuous hydrogen spillover pathway throughout the membrane. This synergistic MMM design leads to substantial improvements in both hydrogen transport and selectivity. At an optimal loading of 28 wt% Pd@ZIF‐67 gel, the MMMs exhibit a H2 permeability of 3620 Barrer and a remarkable 417% enhancement in H2/CH4 selectivity (24.9), surpassing the 2008 upper bound. This approach paves the way for the development of advanced materials tailored for gas separation applications. [ABSTRACT FROM AUTHOR]

The conversion of CO2 into formate through electrochemical methods is emerging as an elegant approach for industrial‐scale CO2 utilization in the near future. Although Bismuth (Bi)‐based materials have shown promise thank to their excellent selectivity, their limited reactivity remains a challenge. Herein, this study demonstrates a significant enhancement in the CO2‐to‐formate efficiency of Bi by incorporating ruthenium (Ru) atomic species. Ru single atom doped Bi exhibited a nearly twofold higher partial current density compared with pure Bi and Ru clusters doped Bi, while over 95% Faradaic efficiency (FE) is maintained. Through comprehensive investigations using a combined approach of electrochemical techniques, operando spectroscopy, and theoretical calculations, this study elucidates that the presence of Ru single atom promotes H2O dissociation and H* migration to Bi sites for CO2‐to‐formate conversion by significantly reducing the energy barrier via a H* spillover path. Besides, it is constructed Ru–Bi bridge sites for efficient CO2 hydrogenation via a non‐spillover path, which served as the major mechanism for CO2‐to‐formate conversion in Ru single atom doped Bi. [ABSTRACT FROM AUTHOR]

Herein, a heterogeneous structure of Ni–Mo catalyst comprising Ni4Mo nanoalloys decorated on a MoOx matrix via electrodeposition is introduced. This catalyst exhibits remarkable hydrogen evolution reaction (HER) activity across a range of pH conditions. The heterogeneous Ni–Mo catalyst showed low overpotentials only of 24 and 86, 21 and 60, and 37 and 168 mV to produce a current density of 10 and 100 mA cm−2 (η10 and η100) in alkaline, acidic, and neutral media, respectively, which represents one of the most active catalysts for the HER. The enhanced activity is attributed to the hydrogen spillover effect, where hydrogen atoms migrate between the Ni4Mo alloys and the MoOx matrix, forming hydrogen molybdenum bronze as additional active sites. Additionally, the Ni4Mo facilitated the water dissociation process, which helps the Volmer step in the alkaline/neutral HER. Through electrochemical analysis, in situ Raman spectroscopy, and density functional theory calculations, the fast HER mechanism is elucidated. [ABSTRACT FROM AUTHOR]

The development of efficient and durable bifunctional electrocatalysts is essential for hydrogen production from acidic water splitting. Herein, a TiO2 nanotube‐loaded Co‐doped Ru nanoparticle catalyst (RuCo/TiO2 NTs) is reported that exhibits excellent activity and stability toward acidic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The Ru─O─Ti bonding is enhanced by Co doping, and the metal carrier interaction between Ru nanoparticles and TiO2 NTs is enhanced, which effectively stabilizes Ru species during OER and initiates hydrogen spillover accelerating HER kinetics. As a result, RuCo/TiO2 NTs catalyst requires only 156 mV OER overpotential and 17 mV HER overpotential to achieve a current density of 10 mA cm−2 with a stability more than 500 h in acidic conditions. More importantly, benefiting from the excellent bifunctional activities, the proton exchange membrane electrolyte assembled from RuCo/TiO2 NTs has excellent activity and robust stability (1000 h). This work opens a new avenue for the efficient energy conversion devices. [ABSTRACT FROM AUTHOR]

The hydrogen spillover mechanism of metal‐supported electrocatalyst can significantly improve HER activity. However, the rational design of binary heterojunction hydrogen spillover electrocatalysts remains a challenge. Here, a NiSe2‐Ni5P4 heterojunction electrocatalyst with superaerophobic structure is synthesized by using a simple substrate self‐derived strategy. Experimental characterization and theoretical calculation reveal the hydrogen spillover mechanism of NiSe2‐Ni5P4 heterogeneous electrocatalyst. NiSe2 and Ni5P4 synergistically promote the adsorption/dissociation of H2O and the adsorption of H*, respectively. The smaller ΔΦ effectively reduced the electron density at the interface, weakening the proton adsorption at the interface and promoting the migration of H* from NiSe2 to Ni5P4. The NiSe2‐Ni5P4 exhibits excellent HER activity in alkaline electrolyte, requiring only a potential of 65, 270 mV to achieve a current density of 10, 500 mA cm−2, respectively, and a stability of up to 200 h. Moreover, the design of NiSe2‐Ni5P4 with superaerophobic structure can reduce the deposition of impurity ions on the electrode surface and avoid Cl− corrosion of the electrode, which results in NiSe2‐Ni5P4 showing better HER activity and stability than commercial Pt/C in brackish water. This study deepens the understanding of hydrogen spillover mechanism of binary heterojunction electrocatalysts, broadens the application of hydrogen production in complex water quality. [ABSTRACT FROM AUTHOR]

The substantial promotion of hydrogen evolution reaction (HER) catalytic performance relies on the breakup of the Sabatier principle, which can be achieved by the alternation of the support and electronic metal support interaction (EMSI) is noticed. Due to the utilization of tungsten disulfides as support for platinum (Pt@WS2), surprisingly, Pt@WS2 demands only 31 mV overpotential to attain 10 mA cm−2 in acidic HER test, corresponding to a 2.5‐fold higher mass activity than benchmarked Pt/C. The pH dependent electrochemical measurements associated with H2‐TPD and in situ Raman spectroscopy indicate a hydrogen spillover involved HER mechanism is confirmed. The WS2 support triggers a higher hydrogen binding strength for Pt leading to the increment in hydrogen concentration at Pt sites proved by upshifted d band center as well as lower Gibbs free energy of hydrogen, favourable for hydrogen spillover. Besides, the WS2 shows a comparably lower effect on Gibbs free energy for different Pt layers (−0.50 eV layer−1) than carbon black (−0.88 eV layer−1) contributing to a better Pt utilization. Also, the theoretical calculation suggests the hydrogen spillover occurs on the 3rd Pt layer in Pt@WS2; moreover, the energy barrier is lowered with increment in hydrogen coverage on Pt. Therefore, the boosted HER activity attributes to the EMSI effect caused hydrogen spillover and enhancement in Pt utilization efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • A unique W-doped NiS x /Ni@Cu heterointerface was developed by electrodeposition. • W-doped NiS x /Ni heterointerface can lower the HER kinetic barrier. • The W-NiS x /Ni@Cu exhibits an attractive HER activity with a low overpotential of 38 mV at 10 mA cm−2. • The DFT calculations reveal the enhanced water dissociation and H intermediate desorption. Promoting water dissociation and H intermediate desorption play a pivotal role in achieving highly efficient hydrogen evolution reaction (HER) in alkaline media but remain a great challenge. Herein, we rationally develop a unique W-doped NiS x /Ni heterointerface as a favorable HER electrocatalyst which was directly grown on the Cu nanowire foam substrate (W-NiS x /Ni@Cu) by the electrodeposition strategy. Benefiting from the rational design of the interfaces, the electronic coupling of the W-NiS x /Ni@Cu can be efficiently modulated to lower the HER kinetic barrier. The obtained W-NiS x /Ni@Cu exhibits an enhanced HER activity with a low overpotential of 38 mV at 10 mA cm−2 and a small Tafel value of 27.5 mV dec−1, and high stability during HER catalysis. In addition, in-situ Raman spectra reveal that the Ni2+ active sites preferentially adsorb OH intermediate. The theoretical calculation confirms that the water dissociation is accelerated by the construction of W-NiS x /Ni heterointerface and H intermediate desorption can be also promoted by H spillover from S active sites in W-NiS x to Ni active sites in metal Ni. This work offers a valuable reference for rational designing heterointerface of electrocatalysts and provides an available method to accelerate the HER kinetics for the ampere-level current density under low overpotential. [ABSTRACT FROM AUTHOR]

Hydrogen spillover in metal‐supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental mechanism, especially at the metal–metal interface, remains further explored, impeding relevant catalyst design. Here, we theoretically profile that a large free energy difference in hydrogen adsorption on two different metals (|ΔGH‐metal(i)−ΔGH‐metal(ii)|) induces a high kinetic barrier to hydrogen spillover between the metals. Minimizing the difference in their d‐band centers (Δϵd) should reduce |ΔGH‐metal(i)−ΔGH‐metal(ii)|, lowering the kinetic barrier to hydrogen spillover for improved electrocatalytic hydrogenation. We demonstrated this concept using copper‐supported ruthenium–platinum alloys with the smallest Δϵd, which delivered record high electrocatalytic nitrate hydrogenation performance, with ammonia production rate of 3.45±0.12 mmol h−1 cm−2 and Faraday efficiency of 99.8±0.2 %, at low energy consumption of 21.4 kWh kgamm−1. Using these catalysts, we further achieve continuous ammonia and formic acid production with a record high‐profit space. [ABSTRACT FROM AUTHOR]

Developing an efficient strategy to replace the conventional synthesis method for producing isoindolinone (IIO) scaffold, a crucial structural motif for constructing pharmaceutical molecules, remains to be a great challenge. Herein, a single‐atom Pd/TiO2 tandem catalysis has been developed for the IIO scaffold synthesis by using readily available phthalic anhydride (PA), ammonia, and H2. The single‐atom Pd/TiO2 catalyst demonstrates superior catalytic performance, achieving a PA conversion of 99 %, an IIO selectivity of 91 %, and a turnover frequency (TOF) up to 4807 h−1. This exceptional performance can be attributed to the tandem catalysis between TiO2 support and single‐atom Pd. The TiO2 efficiently catalyzes the conversion of PA with ammonia to form phthalimide (PAM), subsequently transformed into IIO over TiO2 through the reaction of PAM with NH3 and the spillover hydrogen species derived from single‐atom Pd. Notably, NH3 functions not only as a reactant but also as a promoter to accelerate the reduction of amides combined with the Pd/TiO2 catalyst. This tandem catalysis of a single‐atom Pd/TiO2 catalyst provides a promising strategy for the synthesis of the crucial IIO platform molecules. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalyst in sulfides for hydrogen evolution reaction (HER) still poses challenges due to the lack of understanding the role of sulfide heterointerface. Here, we report a sulfide heterostructure RuSx/NbS2, which is composed of 3R‐type NbS2 loaded by amorphous RuSx nanoparticles with S−S bonds formed at the interface. As HER electrocatalyst, the RuSx/NbS2 shows remarkable low overpotential of 38 mV to drive a current density of 10 mA cm−2 in acid, and also low Tafel slope of 51.05 mV dec−1. The intrinsic activity of RuSx/NbS2 is much higher than that of Ru/NbS2 reference as well as the commercial Pt/C. Both experiments and theoretical calculations unveil a reversed charge transfer at the interface from NbS2 to RuSx that driven by the formation of S−S bonds, resulting in electron‐rich Ru configuration for strong hydrogen adsorption. Meanwhile, electronic redistribution induced by the sulfide heterostructure facilitates hydrogen spillover (HSo) effect in this system, leading to accelerated hydrogen desorption at the basal plane of NbS2. This study provides an effective S−S bond strategy in sulfide heterostructure to synergistically modulate the charge transfer and adsorption thermodynamics, which is very valuable for the development of efficient electrocatalysts in practical applications. [ABSTRACT FROM AUTHOR]

Pt automatically adsorbed on oxygen vacancy of TiO2 via an in situ interfacial redox reaction, resulting in atomically dispersion of Pt on TiO2. In the upgrading of lignin‐derived 4‐propylguaiacol, single‐atom catalyst (SAC) Pt/TiO2−H achieved a conversion of 96.9 % and a demethoxylation selectivity of 93.3 % under 3 MPa H2 at 250 °C for 3 h, markedly different from the performance of nanoparticle counterpart that gave deep deoxygenation selectivity over 99.0 %. The high demethoxylation activity of SAC Pt/TiO2−H is mainly attributed to its weak hydrogen spillover capacity that suppressed the benzene ring hydrogenation and the deep deoxygenation. Additionally, SAC Pt/TiO2−H reduced the energy barrier of CAr−OCH3 bond cleavage and accordingly lowered the Gibbs free energy of the demethoxylation reaction. This facile method could fabricate single‐atom Au, Pd, Ir, and Ru supported on TiO2−H, demonstrating the generality of this strategy for the establishment of a library of SACs. Moreover, SAC exhibited versatile capacity in demethoxylation of different lignin‐derived monomers and high stability. This study showcases the superiority of atomically dispersed metal catalysts for selective demethoxylation reactions and proposes a renewable alternative to fossil‐based 4‐alkylphenols through upgrading of lignin‐derived monomers. [ABSTRACT FROM AUTHOR]

Interparticle hydrogen spillover is the phenomenon of H migration over different catalyst particles, which should be a physical mixture of at least two solid catalysts. In this review, we analyze examples of enhanced catalysis based on interparticle (reverse) hydrogen spillover. Simple physical mixtures of powdered catalysts containing metal catalysts of H2 dissociation/recombination and solid catalysts with active sites for substrate activation significantly enhance catalytic reactions. These reactions include aromatic hydrogenation, CO2 methanation, and the deoxydehydration of polyols, aromatization of lower paraffins, and direct coupling of benzene and alkanes. The acceleration effect and proposed reaction pathway of each example involving interparticle (reverse) hydrogen spillover are summarized. Simple reaction systems comprising physical mixtures of at least two powdery solid catalysts should enable unique catalysis in the future with the aid of interparticle (reverse) hydrogen spillover. [ABSTRACT FROM AUTHOR]

Alkaline water splitting has shown great potential for industrial‐scale hydrogen production. However, its broad application is constrained by hydrogen evolution reaction (HER) electrocatalysts, which struggle to achieve optimal current density at low overpotential. The utilization of the hydrogen spillover effect to augment the performance of HER represents a burgeoning area of research. Although previous studies mainly focused on hydrogen spillover in acidic media, the latest studies have shown that hydrogen spillover also exists under alkaline conditions, and its role in improving HER performance cannot be ignored. This review examines the mechanisms of HER under acidic and alkaline conditions, elucidating the distinctive behavior of hydrogen spillover in these environments and its influence on catalytic processes. At the same time hydrogen spillover characterization methods are systematically summarized, these technologies for understanding and control of hydrogen release process provides strong support. Finally, the recent electrocatalysts that enhance the catalytic performance of alkaline HER by hydrogen spillover effect are comprehensively sorted out and summarized. This review not only demonstrate the practical value of hydrogen spillover under alkaline conditions, but also provide new directions for future design and optimization of electrocatalysts. [ABSTRACT FROM AUTHOR]

The effectuation of pH‐universal electrocatalysis is highly attractive but still challenging for the hydrogen evolution reaction (HER). It appeals for not only the facilitated electron transport but also the kinetical proton mass transfer. In this study, a via‐hole Ru/MoO2 confined heterostructure is profiled as a metal‐support platform for the electron/mass transfer‐boosted pH‐universal HER studies. It is indicated that the as‐formed Ru─O─Mo bridge can modulate the electronic transport at the interface, and the proton adsorption and transfer are kinetically derived by the intensified metallic Ru─Ru bond. Resultantly, the Ru/MoO2 heterostructure stably attains the Pt‐beyond HER activity with an ultralow overpotential of 9.2 mV at 10 mA cm−2 in 1 m KOH, and also achieves the competitive HER activity and stability in the acidic/neutral electrolytes. Both the experimental and computational results reveal the accelerated HER kinetics is attributable to the intensive mass transfer through the interfacial Ru→MoO2 hydrogen spillover effect. This work opens up the opportunities to rationalize the advanced metal‐support HER electrocatalysts through the interfacial hydrogen spillover effect and metallic bond engineering. [ABSTRACT FROM AUTHOR]

The reverse water‐gas shift (RWGS) reaction serves as a critical pathway for converting CO2 into diverse chemicals. The Mars–van Krevelen (MvK) mechanism, which leverages lattice oxygen as the oxidant and oxygen vacancies as reductants, offers an alternative catalytic strategy for the selective RWGS reaction. While Mn‐substituted SrTiO3 (i. e., SrTi0.8Mn0.2O3) has been shown to promote the RWGS reaction selectively via the MvK mechanism, achieving a sufficient conversion of CO2 necessitates elevated temperatures. This study investigated the effect of Pd‐loaded SrTi0.8Mn0.2O3 on the activation of adsorbed H2 molecules, which generated oxygen vacancies and enhanced CO2 conversion. Notably, 1.0 wt % Pd‐loaded SrTi0.8Mn0.2O3 yielded 13.4 % of CO at 673 K, whereas pristine SrTi0.8Mn0.2O3 and Pd‐loaded SrTiO3 yielded negligible or minimal amount of CO. Hydrogen temperature‐programmed reduction and X‐ray absorption spectroscopy measurements revealed that Pd promoted the formation of oxygen vacancies via both thermodynamic and kinetic mechanisms. Fourier transform infrared spectroscopy and kinetic studies revealed that the RWGS reaction over Pd‐loaded SrTi0.8Mn0.2O3 proceeded primarily via the MvK mechanism with a partial contribution from the Langmuir–Hinshelwood mechanism. This study underscores the effectiveness of combining metal and MvK‐type catalysts to enhance the efficiency of the RWGS reaction. [ABSTRACT FROM AUTHOR]

Graphene-based nanostructures loaded with transitional metallic atoms have been identified as promising materials for hydrogen storage. In this study, we investigate the adsorption and spillover of hydrogen on a single transitional metal atom incorporated graphene (TM-Gr) through density functional theory (DFT) calculations. Specifically, we explore the geometric and electronic properties of 20 different TM-Gr structures. Our findings reveal that Y-Gr and Sc-Gr exhibit the most favorable H atom adsorption, while Mn-Gr and Cr-Gr are more suitable for H spillover. Additionally, feature importance analysis highlights that Bader charge accumulated in H atom, C-H bond length, and work function of TM-Gr are the three most important features that are sensitive to the activation energy of H spillover. Overall, this work provides valuable insights for the screening of new materials for hydrogen storage. [ABSTRACT FROM AUTHOR]

Hydrogen storage technology is a critical segment for solving future energy problems and is currently an escalating issue for developing our energy economy. In the past two decades, numerous theoretical works and hydrogen storage experiments have been carried out to explore hydrogen storage through the hydrogen spillover method. Hydrogen spillover was found to be an effective method to improve the hydrogen storage performance of carbon – based materials at room temperature. This review mainly addressed the principles of hydrogen spillover, evidence for improving hydrogen storage efficiency, and theoretical studies on the spillover method. In an effort to find some ideas on which materials could be used to store hydrogen at room temperature, we summarized the influencing components of spillover for hydrogen storage from three perspectives: hydrogen storage materials, efficient catalysts, and other factors. Finally, we outlined the current problems and future research directions for hydrogen storage at room temperature and proposed some strategies to address them. [ABSTRACT FROM AUTHOR]

Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges, particularly for the construction of hydrogen evolution reaction (HER) catalysts operating at ampere-level current density. Herein, the unique Ru and RuP2 dual nano-islands are deliberately implanted on N-doped carbon substrate (denoted as Ru-RuP2/NC), in which a built-in electric field (BEF) is spontaneously generated between Ru-RuP2 dual nano-islands driven by their work function difference. Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP2 dual nano-islands, which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density, and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP2 nano-islands through hydrogen spillover process. As a result, the Ru-RuP2/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm−2 along with the superior stability over 1000 h, holding the great promising prospect in practical applications at ampere-level current density. More importantly, this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process, which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density. [ABSTRACT FROM AUTHOR]

Abstract Herein, a heterogeneous structure of Ni–Mo catalyst comprising Ni4Mo nanoalloys decorated on a MoOx matrix via electrodeposition is introduced. This catalyst exhibits remarkable hydrogen evolution reaction (HER) activity across a range of pH conditions. The heterogeneous Ni–Mo catalyst showed low overpotentials only of 24 and 86, 21 and 60, and 37 and 168 mV to produce a current density of 10 and 100 mA cm−2 (η10 and η100) in alkaline, acidic, and neutral media, respectively, which represents one of the most active catalysts for the HER. The enhanced activity is attributed to the hydrogen spillover effect, where hydrogen atoms migrate between the Ni4Mo alloys and the MoOx matrix, forming hydrogen molybdenum bronze as additional active sites. Additionally, the Ni4Mo facilitated the water dissociation process, which helps the Volmer step in the alkaline/neutral HER. Through electrochemical analysis, in situ Raman spectroscopy, and density functional theory calculations, the fast HER mechanism is elucidated.

Highlights Pt–Ni bonded Pt single-atom (SA) catalyst, rather than classic Pt–O bonded SA catalyst, was successfully constructed. The electronic states of Pt SA catalyst were deeply regulated and negatively charged Pt δ− was realized. Pt–Ni bonded Pt SA catalyst-enhanced absorbability for activated hydrogen atoms and promoted hydrogen absorption.

Highlights: Pt–Ni bonded Pt single-atom (SA) catalyst, rather than classic Pt–O bonded SA catalyst, was successfully constructed. The electronic states of Pt SA catalyst were deeply regulated and negatively charged Ptδ− was realized. Pt–Ni bonded Pt SA catalyst-enhanced absorbability for activated hydrogen atoms and promoted hydrogen absorption. Single-atom (SA) catalysts with nearly 100% atom utilization have been widely employed in electrolysis for decades, due to the outperforming catalytic activity and selectivity. However, most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates, which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts. In this work, Pt–Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)2 nanosheet arrays. Based on the X-ray absorption fine structure analysis and first-principles calculations, Pt SA was bonded with Ni sites of amorphous Ni(OH)2, rather than conventional O sites, resulting in negatively charged Ptδ−. In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms, which were the essential intermediate for alkaline hydrogen evolution reaction. The hydrogen spillover process was revealed from amorphous Ni(OH)2 that effectively cleave the H–O–H bond of H2O and produce H atom to the Pt SA sites, leading to a low overpotential of 48 mV in alkaline electrolyte at −1000 mA cm−2 mg−1Pt, evidently better than commercial Pt/C catalysts. This work provided new strategy for the controllable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states. [ABSTRACT FROM AUTHOR]

Efficient water dissociation to atomic hydrogen (H*) with restrained recombination of H* is crucial for improving the H* utilization for electrochemical dechlorination, but is currently limited by the lack of feasible electrodes. Herein, we developed a monolithic single‐atom electrode with Co single atoms anchored on the inherent oxide layer of titanium foam (Co1−TiOx/Ti), which can efficiently dissociate water into H* and simultaneously inhibit the recombination of H*, by taking advantage of the single‐atom reverse hydrogen spillover effect. Experimental and theoretical calculations demonstrated that H* could be rapidly generated on the oxide layer of titanium foam, and then overflowed to the adjacent Co single atom for the reductive dechlorination. Using chloramphenicol as a proof‐of‐concept verification, the resulting Co1−TiOx/Ti monolithic electrode exhibited an unprecedented performance with almost 100 % dechlorination at −1.0 V, far superior to that of traditional indirect reduction‐driven commercial Pd/C (52 %) and direct reduction‐driven Co1−N−C (44 %). Moreover, its dechlorination rate constant of 1.64 h−1 was 4.3 and 8.6 times more active than those of Pd/C (0.38 h−1) and Co1−N−C (0.19 h−1), respectively. Our research sheds light on the rational design of hydrogen spillover‐related electrocatalysts to simultaneously improve the H* generation, transfer, and utilization for environmental and energy applications. [ABSTRACT FROM AUTHOR]

In contrast to the energy‐intensive Haber‐Bosch process, the electroreduction of nitrate to ammonia presents a promising alternative. In this work, the Ni2P/Pd6P nanorods (named NiPdP‐NR) are successfully synthesized by using a simple phosphating process with NiIIPdII‐dimethylglyoxime complex (NiIIPdII‐DMG) nanorods as the precursor. Density functional theory calculations and electrochemical experiments prove that the introduction of Pd facilitates hydrogen spillover from Pd to Ni2P modulates the surface electronic structures, and therefore improves the catalytic kinetics of nitrate reduction ultimately. According to the dynamic experiment, the as‐prepared NiPdP‐NR shows high nitrate conversion efficiency (90.6%), selectivity of NH3 (93.4%), high Faradic efficiency (92.6%), and NH3 yield rate (0.908 mmol h−1 mgcat−1) for the nitrate reduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen evolution reaction (HER) shows potential to transition from fossil fuels to green renewable energy. Designed for high efficiency and stability electrocatalyst in pH-universal electrolyte is of great significance but challenging. Herein, a novel electrocatalyst of two-dimensional (2D) Mo 2 TiC 2 T x MXene supported Pt/Ni(OH) 2 (denoted as Pt/Ni(OH) 2 /Mo 2 TiC 2 T x) is reported by hydrogen spillover effect for efficient HER in the full-pH range. The operando electrochemical characterization reveals that the hydrogen spillover phenomenon interactions between multi-functional catalytic sites, e.g. Pt, Ni(OH) 2 and Mo 2 TiC 2 T x , are used to enhance HER performance and expedite HER kinetics. Moreover, theoretical calculation via density functional theory demonstrates the Pt/Ni(OH) 2 /Mo 2 TiC 2 T x possess free energy of absorbed hydrogen close to zero (≈– 0.09 eV), which leads to optimal activity. As expected, the electrocatalyst necessitates the overpotential of 25, 33 and 36 mV at 10 mA cm−2 in acidic, alkaline, and neutral conditions, respectively, which are outperforming Pt/C. This work furtherly demonstrates a new way to design a powerful electrocatalyst for pH-universal HER based hydrogen spillover phenomenon. [Display omitted] • 2D MXene supported Pt/Ni(OH) 2 electrocatalysts with hydrogen spillover effect for efficient HER in the full-pH range. • The operando electrochemical characterizations verified the hydrogen spillover interactions between the catalytic sites. • The theoretical calculations show that the free energy of hydrogen absorption by the electrocatalyst is close to zero. • The electrocatalyst exhibited lower overpotential, higher turnover frequency and mass activity over the wide pH range. [ABSTRACT FROM AUTHOR]

Electrocatalytic alkyne semihydrogenation under mild conditions is a more attractive approach for alkene production than industrial routes but suffers from either low production efficiency or high energy consumption. Here, we describe a tandem catalytic concept that overcomes these challenges. Component (i), which can trap hydrogen effectively, is partnered with component (ii), which can readily release hydrogen for hydrogenation, to enable efficient generation of active hydrogen on component (i) at low overpotentials and timely (i)‐to‐(ii) hydrogen spillover and facile desorptive hydrogenation on component (ii). We examine this concept over bicomponent palladium‐copper catalysts for the production of representative 2‐methyl‐3‐butene‐2‐ol (MBE) from 2‐methyl‐3‐butyne‐2‐ol (MBY) and achieve a record high MBE production rate of 1.44 mmol h−1 cm−2 and a Faraday efficiency of ~88.8 % at a low energy consumption of 1.26 kWh kgMBE−1. With these catalysts, we further achieve 60 h continuous production of MBE with record high profit space. [ABSTRACT FROM AUTHOR]

This study demonstrates the significant effect of incorporating inexpensive transition metal nanoparticles into metal-organic frameworks (MOFs) to improve their room-temperature hydrogen storage properties. Low-cost nanoparticles (Cu, Ni, and CuNi) were incorporated into UiO-66(Zr) via the double-solvent approach (DSA) plus chemical reduction processes. All composites exhibited higher hydrogen storage capacity compared to pure UiO-66 at both room temperature and 60 bar. Notably, the hydrogen spillover efficiency of CuNi nanoparticles loaded in UiO-66 was comparable to that of MOF adsorbents embedded with noble metals such as Pd and Pt. The hydrogen storage capacity of CuNi@UiO-66 was significantly increased from 0.20 wt% to 0.74 wt%. DFT calculations showed that the CuNi alloys facilitated the adsorption and dissociation of hydrogen molecules in comparison to the single metal nanoparticles, thus favoring the hydrogen spillover effect and improving the hydrogen storage performance. This work demonstrates the potential of designing MOF loaded with inexpensive metal nanoparticles for optimized room-temperature hydrogen storage. [Display omitted] • The inexpensive Cu, Ni, and CuNi NPs were doped into UiO-66 using the dual-solvent approach plus chemical reduction method. • The room-temperature hydrogen storage capacity of UiO-66 was improved by incorporating Cu, Ni, and CuNi NPs into UiO-66. • CuNi@UiO-66 showed comparable improvement in room temperature hydrogen storage compared to other MOFs doped with noble metals. • The CuNi alloy enhances H 2 adsorption and dissociation, improving hydrogen storage through spillover effect. [ABSTRACT FROM AUTHOR]

Recently, hydrogen spillover based binary (HSBB) catalysts have received widespread attention due to the sufficiently utilized reaction sites. However, the specific regulation mechanism of spillover intensity is still unclear. Herein, we have fabricated oxygen vacancies enriched Ru/NiMoO4‐x to investigate the internal relationship between electron supply and mechanism of hydrogen spillover enhancement. The DFT calculations cooperate with in situ Raman spectrum to uncover that the H* spillover from NiMoO4‐x to Ru. Meanwhile, oxygen vacancies weakened the electron supply from Ru to NiMoO4‐x, which contributes to dilute the resistance of built‐in electric field (BEF) for hydrogen spillover. In addition, the higher ion concentration in electrolyte will promote the H* adsorption step obviously, which is demonstrated by in situ EIS tests. As a result, the Ru/NiMoO4‐x exhibits a low overpotential of 206 mV at 3.0 A cm−2, a small Tafel slope of 28.8 mV dec−1, and an excellent durability of 550 h at the current density of 0.5 A cm−2 for HER in 1.0 M KOH seawater. [ABSTRACT FROM AUTHOR]

To promote sustainability, it is essential to make use of biomass waste to create resources that can be transformed into mesoporous materials like silicates. These materials can be used as effective adsorbents for solid-state H 2 storage systems. To meet the requirements of these systems, materials must be inexpensive, possess high specific surface areas, have proper pore arrangements, and exhibit reasonable H 2 uptake. In this study, sustainable rice husk ash-derived MCM-41-RHA and SBA-15-RHA mesoporous silica materials were developed. These materials were engineered with different levels of Ni loading (2.5–10 wt%) and are used for H 2 storage. The prepared MCM-41-RHA and SBA-15-RHA materials have a high BET-specific surface area of 1092.6 m2/g and 539.2 m2/g, respectively, with a mesopore distribution. The best results were observed for samples with a Ni loading of 5 wt%, such as MCM-41-RHA-Ni5 and SBA-15-RHA-Ni5, which demonstrated the highest H 2 uptake of 3.64 wt% and 2.48 wt%, respectively, at 77 K and 1 bar. This was due to the strong interaction between the adsorbent and split over hydrogen despite the decrease in the BET-specific surface area after the incorporation of Ni. The enhanced interaction was evidenced by the increased isosteric heat of adsorption observed for MCM-41-RHA-Ni5 and SBA-15-RHA-Ni5, ranging from 21.1 to 8.1 kJ/mol, in contrast to the range of 6.9 to 4.1 kJ/mol for the pristine MCM-41-RHA and SBA-15-RHA. After five successive H 2 uptake/release cycles, more than 92 % of the initial capacity was retained. This study presents a sustainable and cost-effective RHA-derived mesoporous silica material decorated with Ni- nanoparticles for solid-state H 2 storage. [Display omitted] • Synthesis of RHA-derived SBA-15-RHA and MCM-41-RHA as sustainable H 2 storage materials. • Decoration of SBA-15-RHA and MCM-41-RHA with Ni to induce H 2 spillover effect. • SBA-15-RHA-Ni5 and MCM-41-RHA-Ni5 exhibit the highest H 2 uptake of 2.48 and 3.64 wt%, respectively, at 77 K and 1 bar. • A high degree of Ni decoration (>5 wt%) results in a decreased H 2 uptake capacity due to the aggregation of NiO. [ABSTRACT FROM AUTHOR]

It remains challenging to design alkaline hydrogen evolution reaction (HER) electrocatalyst able to stably operate at ampere-level current density. In this work, we successfully synthesized heterostructured Ni 3 S 2 /Cr 2 S 3 nanosheets on nickel foam (Ni 3 S 2 /Cr 2 S 3 /NF) for high current HER electrocatalysis in alkaline media. As-prepared Ni 3 S 2 /Cr 2 S 3 /NF reaches 0.5 and 1.0 A cm−2 currents at 230 and 333 mV overpotential, respectively. After 50 h test at 0.5 A cm−2, the potential of Ni 3 S 2 /Cr 2 S 3 /NF remained almost unchanged. This impressive HER performance stems from its unique hybridization nature enabled hydrogen spillover, in which Cr 2 S 3 efficiently catalyzes the Volmer step, i.e., water dissociation to generate hydrogen, and the latter further transports to neighboring Ni 3 S 2 via spillover to facilitate the molecular hydrogen formation. This work provides a feasible strategy to synthesize efficient and durable HER catalysts for ampere-level water splitting. • Heterostructured bimetallic sulfide Ni 3 S 2 /Cr 2 S 3 was prepared by a one-step hydrothermal method. • The catalyst exhibits remarkable HER activity under alkaline conditions. • The hydrogen spillover provides an effective way to accelerate multi-step HER through relay catalysis. • The catalyst requires low overpotentials of 333 mV to reach 1000 mA cm−2 with long-term durability. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation utilizing sustainably produced hydrogen and CO2 derived from industrial exhaust gas represents a pivotal technology for chemical energy storage and climate change mitigation. This work aims to identify the best combination of catalyst support, synthesis method and promotor for In2O3/ZrO2 catalysts in a typical fixed‐bed configuration. Intense characterization using ICP‐OES, XRD, XPS, N2‐physisorption, CO2‐TPD, H2‐TPR and SEM‐EDX provide molecular insights into the different effects caused by various synthesis methods and doping elements. Doping the most promising In2O3/ZrO2 (M‐SG) catalyst with 0.7 wt. % NiO by wetness impregnation using an ethanol/water mixture as a solvent, an increased methanol production rate of 0.497 gMeOH ⋅gcat1 ${{{\rm { \hskip0.17em}}{\rm { g}}}_{{\rm { cat}}}^{{\rm { 1}}}}$ ⋅ h−1 could already be achieved at 250 °C. Hereby, the low amount of highly dispersed NiO promotes H2 activation via hydrogen spillover, leading to sustained catalytic activity for 100 hours of time‐on‐stream. [ABSTRACT FROM AUTHOR]

The activation of molecular hydrogen is a key process in catalysis. Here, we demonstrate how polyoxometalate (POM)‐based heterogeneous compounds functionalized with Platinum particles activate H2 by synergism between a hydrogen spillover mechanism and electron‐proton transfer by the POM. This interplay facilitates the selective catalytic reduction of olefins and nitroarenes with high functional group tolerance. A family of polyoxotungstates covalently functionalized with boronic acids is reported. In the solid‐state, the compounds are held together by non‐covalent interactions (π–π stacking and hydrogen bonding). The resulting heterogeneous nanoscale particles form stable colloidal dispersions in acetonitrile and can be surface‐functionalized with platinum nanoparticles by in situ photoreduction. The resulting materials show excellent catalytic activity in hydrogenation of olefins and nitrobenzene derivatives under mild conditions (1 bar H2 and room temperature). [ABSTRACT FROM AUTHOR]

A series of palladium-modified (Pd-modified) CuO-ZnO-Al2O3 (CZA) catalysts with various Pd loadings (0.3 wt% to 2.4 wt%) were prepared using the wetness impregnation method, on two CZA supports with different structures that are CZA-aged precursor composed of a mixture of zincian-malachite and hydrotalcite-like phases (CZA-zH), and CuO-ZnO-Al2O3 metal oxide nanoparticles (CZA-MO). Enhancement on catalytic activity can be observed on both Pd-modified CZA catalysts in a temperature range of 180–240 °C for methanol synthesis via CO2 hydrogenation. Pd/CZA-zH catalysts exhibited a more efficient and stable production of methanol at a relatively low reaction temperature of 180 °C for 100 hrs of reaction. The improvement of activity is mainly ascribed to a higher surface area and abundant oxygen-containing functional groups (e.g., –OH) of CZA-zH support, which is beneficial for better adsorption and distribution of Pd promoter. Hydrogen temperature programmed reduction and X-ray photoelectron spectroscopy results demonstrated a better interaction between Pd and Cu on Pd/CZA-zH catalysts via enhanced reducibility of CuO, and peak shift of Cu to a lower binding energy. The difference in the efficient utilization of hydrogen spillover effect of Pd promoter over two CZA supports resulted in the different performances for methanol synthesis under mild reaction conditions.

Herein, we reported that the platinum (Pt) clusters encapsulated into sodalite (SOD) zeolite as catalyst exhibited 100 % selectivity at 100 % conversion in the selective hydrogenation of p‐chloronitrobenzene to p‐chloroaniline via hydrogen spillover. The direct interaction between p‐chloronitrobenzene and encapsulated Pt was prevented by the shape selectivity of SOD zeolite, reactants were thereby adsorbed onto zeolite outer surface to facilitate the hydrogenation proceeding by hydrogen spillover process. The further kinetic study and DFT calculation showed the excellent catalytic selectivity was ascribed to the much faster rate of hydrogenation of adsorbed nitro group than that of adsorbed C−Cl group. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen spillover effects will significantly improve the activity of photocatalytic hydrogen evolution reactions (HER), while their introduction and optimization require the construction of an excellent metal/support structure. In this study, we have synthesized Ru/TiO 2-x catalysts with controlled oxygen vacancy (OVs) concentrations using a simple one-pot solvothermal method. The results show that Ru/TiO 2-x3 with the optimal OVs concentration exhibits an unprecedentedly high H 2 evolution rate of 13604 μmol·g−1·h−1, which was 45.7 and 2.2 times higher than that of TiO 2-x (298 μmol·g−1·h−1) and Ru/TiO 2 (6081 μmol·g−1·h−1). Controlled experiments, detailed characterizations, and theoretical calculations have revealed that the introduction of OVs on the carrier contributes to the hydrogen spillover effect in the metal/support system photocatalyst and that the process of hydrogen spillover in this system can be optimized by modulating the OVs concentration. This study proposes a strategy to decrease the energy barrier of hydrogen spillover and enhance photocatalytic HER activity. Moreover, it investigates the effect of OVs concentration on the hydrogen spillover effect in the photocatalytic metal/supports system. [ABSTRACT FROM AUTHOR]

Both the adsorption/dissociation of water molecules and hydrogen intermediate (H*) are the major limitations to hydrogen evolution reaction (HER). Herein, the modulation of electronic structure and geometric configuration are combined to design one-dimensional electrocatalyst with outstanding HER activity in a wide pH range. The catalyst was composed of molybdenum trioxide doped molybdenum nickel alloy supported by copper nanowires (MoO3-MoNi4@Cu NWs). As revealed by the experimental characterizations and theoretical calculations, Cu NWs act as the electron donator to MoNi4, resulting in up shift of the d-band center in MoNi4, thus expediting H2O adsorption and dissociation. Moreover, the introduction of amorphous MoO3 sets up a unique geometric configuration on MoNi4 for the accelerated H* transfer via hydrogen-bond and hydrogen spillover. This work provides a synergetic route for constructing HER freeway and promotes further investigations on more versatile electrocatalysis involving H2O or H*. [ABSTRACT FROM AUTHOR]

[Display omitted] • CNT supported Ru single atoms have been associated to Ru, Pd and Ni particles. • Hydrogen spillover induced a cooperative catalysis between supported Pd and Ni particles and Ru single atoms. • The RuNi/CNT catalyst contains a cocktail of catalytic species including isolated Ru single atoms and Ru single atoms on Ni particles. • The RuNi/CNT catalyst shows much better performances in terms of activity and selectivity compared to the monometallic systems. • DFT calculations revealed that the active species is a Ru SA @Ni NP single atom alloy. Reaching high selectivity at high conversion and high rate in the industrially important selective hydrogenation of α,β-unsaturated aldehydes is a challenging task. Among current approaches reported in the literature, high selectivity towards the unsaturated alcohol or saturated aldehyde is generally achieved at the expense of activity. The use of bimetallic systems can lead either to selectivity or to activity enhancement, but generally not to both. Herein, we show that, for cinnamaldehyde hydrogenation, combining Ni nanoparticles (Ni NP) and Ru single atoms (Ru SA) on CNTs allows improvement of the hydrocinnamaldehyde selectivity, while obtaining a remarkable activity. The STY of Ru SA -Ni NP /CNT is approximately 60 times higher than that of the Ru SA /CNT and 10 times higher than that of the Ni NP /CNT. Importantly, the resulting catalyst shows 94% selectivity at 99% conversion and a good stability in flow. Insights into the cooperative "cocktail"-type catalysis between Ni NP and Ru SA were revealed from density functional theory calculations. [ABSTRACT FROM AUTHOR]

I, hydrogen dissociation; II hydrogen adsorption; III, hydrogen transfer from initiator to acceptor or spillover; and IV, Co reduction and water removal. [Display omitted] • Os-Co complexes placed inside and outside hollow carbon spheres were made. • The new materials were fully characterised. • Spillover effects from Os to Co were studied. • PDF analysis aided in determining the Co oxidation states. The PDF method is used to study short- and intermediate-range order in materials on the nanoscale. • Fischer-Tropsch studies on the Os-Co-HCS catalysts were consistent with spillover effects. Little attention has been given to the use of osmium as a promoter for Fischer-Tropsch Synthesis (FTS). In previous studies, Os has proven to be a poor FT catalyst, but its use as a catalyst promoter has not been studied. In this study, the synthesis and use of Os nanoparticles supported on/in Co@HCS (HCS = hollow carbon sphere) FT catalysts are reported. The hollow morphology of the HCSs was exploited to study the influence of Os promoter nanoparticle location relative to the Co 3 O 4 nanoparticles (d Co = 3.5–12.5 nm) and on the effect of Os on the reduction behaviour and activity of the Co FT catalyst. Os (0.1, 0.5 and 1 wt%) nanoparticles were loaded both inside and outside the HCSs, while the Co 3 O 4 particles (Co 10 wt%) were loaded inside of the HCSs to give CoOs@HCS and Os/(Co@HCS). Electron microscopy, in situ PXRD, PDF, TGA, BET, and TPR studies revealed that both catalysts were successfully synthesized. The use of ex-situ PXRD, PDF and TPR studies provided information on the Co phases and reduction pathways of the Co 3 O 4 metal catalyst and the spillover effect from Os to Co. Co 3 O 4 and CoO phases were observed for the CoOs@HCS and Os/(Co@HCS) catalysts. More interesting was the observation of the Co fcc phase in the OsCo@HCS catalysts, indicating the importance of the Os-Co interaction. The catalyst with Co and Os close together (primary spillover process) gave a higher Fischer-Tropsch activity (38.5–46.4 × 10−6 mol CO /g Co.s) and higher C 5+ production than both the unpromoted catalyst (27.8 × 10−6 mol CO /g Co.s), and the catalysts where Os and Co were separated (25.1–36.4 × 10−6 mol CO /g Co.s) by the mesoporous carbon shell (secondary spillover effect). The studies on both CoOs@HCS and Co/(Os@HCS) catalysts have indicated for the first time the effect of Os on Co catalysts, with particular reference to FTS. [ABSTRACT FROM AUTHOR]

Hydrogen spillover is an elusive process, and its characterization, using experimental probes and ab initio modeling, poses a serious challenge. In this work, the nuclear quantum dynamics of hydrogen in a palladium-decorated cubic polymorph of tungsten oxide, Pd/cWO3, are characterized by the technique of neutron Compton scattering augmented by ab initio harmonic lattice modeling. The deeply penetrating nature of the neutron scattering process, the lack of spectroscopic selection rules, the inherent high sensitivity to hydrogen, the high energy and momentum resolution for hydrogen, and the mass selectivity of the technique render the neutron Compton scattering a very potent and unique tool for investigating the local dynamics of hydrogen species in bulk matrices. The total neutron Compton scattering response of hydrogen is described in terms of the hydrogen momentum distribution. The distribution is deconvoluted under the assumption of three pools of hydrogen with distinctly different nuclear quantum dynamical behavior: (i) hydrogen-terminated beta-palladium hydride, (ii) hydrogen in acid centers (OH+ groups) on the surface of the cubic phase of tungsten oxide, and (iii) quasi-free atomic hydrogen inside the saturated hydrogen bronze resulting from the spillover process. The ab initio modeling of lattice dynamics yields theoretical predictions for the values of the widths of proton momentum distributions in the first two hydrogen pools, which allows for obtaining the contribution and the width of the momentum distribution of the quasi-free atomic hydrogen resulting from the hydrogen spillover process. The analysis reveals that the local binding strength of the quasi-free hydrogen is characterized by the values of nuclear momentum distribution width, nuclear kinetic energy, and force constant of the underlying potential of the mean force close to those of free, unconstrained hydrogen atomic species in a gas of non-interacting particles described by the Maxwell–Boltzmann distribution. Moreover, this picture of the local dynamics of the quasi-free hydrogen is consistent with the proton polaron model of hydrogen-induced coloration of bulk hydrogenated WO3. [ABSTRACT FROM AUTHOR]

Hydrogenation of phenol to cyclohexanone/cyclohexanol is an important reaction in production of nylon‐6, nylon‐66 and in petroleum industry. Liquid phase phenol hydrogenation over Pd‐CuO/CeO2 was carried out under mild conditions. Palladium impregnated over CuO/CeO2 synthesized by co‐precipitation method showed excellent catalytic activity for phenol hydrogenation (99% conversion with 80% cyclohexanol yield) at 90 °C and 10 bar H2 pressure in water. Commercial 10%Pd/C showed only 8% phenol conversion under identical conditions. The detailed characterization revealed significant improvement in surface area of ceria after addition of CuO and decrease in crystallite size with creation of defects in CeO2 lattice. XPS analysis showed Pd loading on CuO/CeO2 to cause hydrogen spillover on the surface leading to increase in the oxygen vacancies. The interaction of phenol with catalyst surface studied by detailed FTIR analysis, revealed activation of phenol on oxygen vacancy of ceria as phenoxide ion with perpendicular orientation of aromatic ring on catalyst surface. [ABSTRACT FROM AUTHOR]

Hydrogenation of phenol to cyclohexanone/cyclohexanol is an important reaction in production of nylon‐6, nylon‐66 and in petroleum industry. Liquid phase phenol hydrogenation over Pd‐CuO/CeO2 was carried out under mild conditions. Palladium impregnated over CuO/CeO2 synthesized by co‐precipitation method showed excellent catalytic activity for phenol hydrogenation (99% conversion with 80% cyclohexanol yield) at 90 °C and 10 bar H2 pressure in water. Commercial 10%Pd/C showed only 8% phenol conversion under identical conditions. The detailed characterization revealed significant improvement in surface area of ceria after addition of CuO and decrease in crystallite size with creation of defects in CeO2 lattice. XPS analysis showed Pd loading on CuO/CeO2 to cause hydrogen spillover on the surface leading to increase in the oxygen vacancies. The interaction of phenol with catalyst surface studied by detailed FTIR analysis, revealed activation of phenol on oxygen vacancy of ceria as phenoxide ion with perpendicular orientation of aromatic ring on catalyst surface. [ABSTRACT FROM AUTHOR]

The migration of species across interfaces can crucially affect the performance of heterogeneous catalysts. A key concept in using bimetallic catalysts for hydrogenation is that the active metal supplies hydrogen atoms to the host metal, where selective hydrogenation can then occur. Herein, we demonstrate that, following dihydrogen dissociation on palladium islands, hydrogen atoms migrate from palladium to silver, to which they are generally less strongly bound. This migration is driven by the population of weakly bound states on the palladium at high hydrogen atom coverages which are nearly isoenergetic with binding sites on the silver. The rate of hydrogen atom migration depends on the palladium-silver interface length, with smaller palladium islands more efficiently supplying hydrogen atoms to the silver. This study demonstrates that hydrogen atoms can migrate from a more strongly binding metal to a more weakly binding surface under special conditions, such as high dihydrogen pressure.

The migration of species across interfaces can crucially affect the performance of heterogeneous catalysts. A key concept in using bimetallic catalysts for hydrogenation is that the active metal supplies hydrogen atoms to the host metal, where selective hydrogenation can then occur. Herein, we demonstrate that, following dihydrogen dissociation on palladium islands, hydrogen atoms migrate from palladium to silver, to which they are generally less strongly bound. This migration is driven by the population of weakly bound states on the palladium at high hydrogen atom coverages which are nearly isoenergetic with binding sites on the silver. The rate of hydrogen atom migration depends on the palladium-silver interface length, with smaller palladium islands more efficiently supplying hydrogen atoms to the silver. This study demonstrates that hydrogen atoms can migrate from a more strongly binding metal to a more weakly binding surface under special conditions, such as high dihydrogen pressure.

The hydrogen spillover effect (HSPE) plays an important role in heterogeneous catalysis and hydrogen storage as an interfacial phenomenon, which facilitates the improvement of hydrogen storage properties of porous nanomaterials and indirectly or directly affects the reaction performance of multiphase catalytic reactions. The setting-up of the word “hydrogen spillover” opened up a new area to gain insight into the dynamic behavior of migrating hydrogen atoms on a catalyst surface. However, a comprehensive understanding of the HSPE is still lacking. Today, the development of advanced characterization techniques provides increasingly valuable information to further our understanding of the HSPE. Based on these considerations, in this review, we hope to provide some answers to the question “What is hydrogen spillover and how do we recognize it?”. To do this, we will rely on advanced characterization techniques as well as experimental and theoretical studies. Then, we discuss in detail the influences of the HSPE on hydrogen storage performance and the important catalytic effects of the HSPE in catalysis. These effects will be reviewed by looking through the catalytic results obtained in many reactions in thermal catalysis, electrocatalysis, and photocatalysis. Furthermore, based on the application potential of hydrogen spillover, we present some preliminary research proposals and discuss the opportunities and challenges that remain to be faced in this research area.

[Display omitted] • Pt@SSZ-13@β with only spillover hydrogenation is designed and prepared. • Effects of hydrogenation modes on naphthalene hydrocracking are investigated. • Hydrogenation modes influence the reaction pathway of naphthalene hydrocracking. • Pt@SSZ-13@β gave higher yields to BTX than Pt/(SSZ-13@β) and (Pt/SSZ-13)@β. A Pt@SSZ-13@β core-shell catalyst is designed and successfully prepared for investigating the effects of spillover hydrogenation on hydrocracking of naphthalene. The Pt NPs encapsulated in SSZ-13 cages are inaccessible to naphthalene due to its lager size than the pore size of SSZ-13. Thus, hydrogenation functional over Pt@SSZ-13@β is mainly realized via spillover hydrogenation. Pt@SSZ-13@β exhibits higher selectivity to the desired BTX and less naphthenic products than (Pt/SSZ-13)@β and Pt/(SSZ-13@β) at above 90 % naphthalene conversion. These results indicate the hydrogenation modes resulting from the location of the supported Pt NPs in core-structure catalysts can affect the metal-acid balance, and the spillover hydrogenation can effectively suppress the deep hydrogenation of tetralin in hydrocracking of naphthalene, thereby changing the reaction path and improving the selectivity of BTX. In addition, Pt@SSZ-13@β shows a better sulfur-tolerant ability than Pt/(SSZ-13@β). This work provides a new synthetic strategy for preparing zeolite-based bifunctional catalyst. [ABSTRACT FROM AUTHOR]

To determine whether graphene-supported Ti clusters can synergistically store hydrogen through Kubas and spillover effect, we systematically investigate the growth pattern of Ti n (n = 1–10) clusters on pristine and defective graphene and analyze multiple types of bonding states of hydrogen in detail. For pristine graphene, the most stable Ti n (n = 1–10) clusters are the quasi-planar structure except for supported Ti 4 and Ti 5. The Ti dissociation energies and the binding energy of Ti n clusters gradually increase with increasing n , which indicates that larger Ti n clusters tend to form. Efficient spillover will occur on single-site Ti Catalysts at low hydrogen concentration due to the lower hydrogen spillover energy barrier (3.05 eV), while the energy barrier of hydrogen migration from Ti n (n = 2–7) clusters to graphene on the cluster is 5.34–6.82 eV. The Ti: H ratio is a maximum of 1:8 for the single-site Ti catalyst, while decreases with the Ti n cluster increases. Therefore, the pristine graphene-supported Ti nanoclusters are more suitable as substrates for hydrogen adsorbent rather than spillover. The introduced defects make Ti n clusters have three-dimensional conical configurations from n = 4. Ti 3 and Ti 6 are the most stable clusters. Moreover, the migration energy barriers of H atoms on them decrease from 6.54 eV to 6.82 eV–4.32 eV and 3.42 eV, respectively. Our results explain recent experimental phenomena [Appl Phys Lett 2015; 106: 083,901. ACS Energy Lett 2022; 7 (7): 2297–2303] in depth at the molecular level. [Display omitted] Hydrogen can form three different main binding modes on graphene-supported Ti n (n = 2–7) clusters: atomic H, dissociated H 2 , and polarized H 2. • The Ti n /G clusters are quasi-planar except for n = 4,5. • Ti SAC has a lower hydrogen spillover energy barrier (3.05 eV). • H migration barrier from Ti n (n = 2–7) to graphene is 5.34–6.82 eV. • Defects reduce the size of Ti islands and increase the hydrogen storage density. [ABSTRACT FROM AUTHOR]

The hydrogenative ring‐opening of furfurals (furfural and 5‐methylfurfural) to linear diols (1,4‐pentanediol and 2,5‐hexanediol) is of great significance for bioderived fine chemical synthesis. Unfortunately, the catalytic activity and selectivity are unsatisfactory because of the interference of various side reactions, such as overhydrogenation to tetrahydrofurans. Herein, the preparation of an iodine (I) modified Pt‐based catalyst with abundant Pt‐I pairs is reported for the first time and shows high catalytic efficiency for linear diol synthesis with a yield of 80%–90% via the hydrogenative ring‐opening route, whereas bare Pt counterpart only shows tetrahydrofuran synthesis via the overhydrogenation route. The catalytic reaction mechanism shows the in‐situ hydrogen spillover‐promoted H−‐Pt‐I‐H+ pairs not only supply hydrogenation sites for the C=O hydrogenation step but also provide Brønsted acidic sites for the ring‐opening step. This work presents a feasible and convenient strategy for bifunctional catalysis with powerful linear diol synthesis over iodine‐modified noble metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spillover effects reflect bifunctional cascades mediated by gaseous molecular shuttles. • Their hydrogenation on oxides scavenges unreactive metal-bound species. • Scavenging decreases coverages of unreactive species favoring more productive routes. • Inter-function intimacy (without atomic contact) decreases diffusion distances. • Acid-base pairs on γ-Al 2 O 3 activate H 2 and hydrogenate alkadienes and alkenes. Support effects in alkene and arene hydrogenations on metal catalysts attributed to "hydrogen spillover" are shown to reflect the desorption and hydrogenation of Pt-bound intermediates at acid-base pairs on certain oxides (e.g. Al 2 O 3 , TiO 2 , MgO). Toluene-H 2 reactions on Pt nanoparticles dispersed on SiO 2 (Pt/SiO 2) occur on surfaces nearly saturated with a diverse pool of bound species differing in the locations of H-atoms and surface attachments. Their diverse coverages and reactivity cause Pt surfaces to become preferentially occupied by less reactive isomers at the expense of the more competent isomers that account for most hydrogenation turnovers. These less reactive species can desorb from Pt nanoparticles as gaseous methylcyclohexadiene molecules, which diffuse to and react at nearby oxide surfaces; such scavenging increases the relative abundance of the more reactive intermediates at Pt surfaces leading to the rate enhancements inaccurately denoted as "hydrogen spillover." These rate enhancements become less pronounced as mean inter-function distances between Pt nanoparticles and acid-base pairs on oxide surfaces increase, and as methylcyclohexadiene molecules become less effectively scavenged as their rates of mass transfer become consequential. The Al 2 O 3 surfaces considered here catalyze dihydrogen addition to cyclohexadiene and cyclohexene molecules (but not toluene); titration of acid-base pairs by propanoic acid suppresses such reactions, as well as the significant enhancements of toluene-H 2 reaction rates observed when Al 2 O 3 is mixed physically with Pt/SiO 2. The rate enhancements conferred by these bifunctional routes represent a natural consequence of the diverse coverage and reactivity of many different species bound on crowded metal surfaces during arene and alkene hydrogenation reactions. Their desorption as partially-hydrogenated molecules enable their scavenging at a second function present within diffusion distances, without requiring inter-function contact or the surface diffusion of H atoms. [ABSTRACT FROM AUTHOR]

Hydrogen spillover has attracted increasing interests in the field of electrocatalytic hydrogen evolution reaction (HER) in recent years because of their distinct reaction mechanism and beneficial terms for simultaneously weakening the strong hydrogen adsorption on metal and strengthening the weak hydrogen adsorption on support. By taking advantageous merits of efficient hydrogen transfer, hydrogen spillover‐based binary catalysts have been widely investigated, which paves a new way for boosting the development of hydrogen production by water electrolysis. In this paper, we summarize the recent progress of this interesting field by focusing on the advanced strategies for intensifying the hydrogen spillover towards HER. In addition, the challenging issues and some perspective insights in the future development of hydrogen spillover‐based electrocatalysts are also systematically discussed. [ABSTRACT FROM AUTHOR]