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Metal confinement catalyst MoS2/Pt@TD-6%Ti (TD, TS-1/Dendritic mesoporous silica nanoparticles composite) in dendritic hierarchical pore structures was synthesized and showed excellent sulfur-resistance performance and stabilities in catalytic hydrodesulfurization reactions of probe sulfide molecules. The MoS2/Pt@TD-6%Ti catalyst combines the concepts of Pt-confinement effect and hydrogen spillover of Pt noble metal. The modified micropores of Mo/Pt@TD-6%Ti only allow the migration and dissociation of small H2 molecules (0.289 nm), and effectively keep the sulfur-containing compounds (e.g. H2S, 0.362 nm) outside. Thus, the MoS2/Pt@TD-6%Ti catalyst exhibits higher DBT and 4,6-DMDBT HDS activities because of the synergistic effect of the strong H2 dissociation ability of Pt and desulfurization ability of MoS2 with a lower catalyst cost. This new concept combining H2 dissociation performance of noble metal catalyst with the desulfurization ability of transition metal sulfide MoS2 can protect the noble metal catalyst avoiding deactivation and poison, and finally guarantee the higher activities for DBT and 4,6-DMDBT HDS.

The morphologies and the electron property of catalysts play the very important roles in the hydrogenation and dehydrogenation of liquid organic hydrogen carriers (LOHCs) such as dibenzyltoluene (DBT). The different morphologies and pore structures of γ-Al2O3 and MoxC doped γ-Al2O3 were synthesized as the supports for Pt catalysts. After analyzing of various characterizations and catalytic testing, it was found that the large surface area and the mesoporous structure of catalysts are beneficial to both DBT hydrogenation and perhydro-dibenzyltoluene (H18-DBT) dehydrogenation. The doping of MoxC promoted the formation of the smaller Pt nanoparticles and increased Pt dispersion. The forming Pt–Mo structure is beneficial to hydrogen spillover which suppress the formation of by-product. The high Pt dispersion of 0.1 wt% MoxC doped Pt/Al2O3 catalyst plays the positive roles in increasing H18-DBT dehydrogenation activity.

On-site produced hydrogen from ammonia decomposition can directly fuel solid oxide fuel cells (SOFCs) for power generation. The key issue in ammonia decomposition is to improve the activity and stability of the reaction at low temperatures. In this study, proton-conducting oxides, Ba(Zr,Y) O3-δ (BZY), were investigated as potential support materials to load Ni metal by a one-step impregnation method. The influence of Ni loading, Ba loading, and synthesis temperature, of Ni/BZY catalysts on the catalytic activity for ammonia decomposition were investigated. The Ni/BZY catalyst with Ba loading of 20 wt%, Ni loading of 30 wt%, and synthesized at 900 °C attained the highest ammonia conversion of 100% at 600 °C. The kinetics analysis revealed that for Ni/BZY catalyst, the hydrogen poisoning effect for ammonia decomposition was significantly suppressed. The reaction order of hydrogen for the optimized Ni/BZY catalyst was estimated as low as −0.07, which is the lowest to the best of our knowledge, resulting in the improvement in the activity. H2 temperature programmed reduction and desorption analysis results suggested that a strong interaction between Ni and BZY support as well as the hydrogen storage capability of the proton-conducting support might be responsible for the promotion of ammonia decomposition on Ni/BZY. Based on the experimental data, a mechanism of hydrogen spillover from Ni to BZY support is proposed.

The development of an efficient hydrogen spillover (HS) catalyst achieves the stoichiometric chemoselective hydrogenation of NO3− and NO2− into N2 at room temperature, which is extremely challenging. Herein, we report a CuxPd1−x nanowire network (NWN) (x = 7, 5, or 3) with tunable hydrogen spillover rate of formic acid (FA) with polyvinylpyrrolidine imine (PVPI) modifying its surface. The presence of PVPI boosts the catalytic selectivity and activity of CuPd NWN for FA dehydrogenation and, more importantly, serves as a modem to tune the HS rate of FA and to stoichiometrically hydrogenate NO3− and NO2− to N2 at room temperature. The density functional theory (DFT) reveals that the CuPd (130 h−1) has a weaker HS rate than AgPd (390 h−1), but the CuPd (> 99%) has a higher utilization of HS than AgPd (31%). Our studies demonstrate a new approach of tuning the FA HS rate and maximizing the application for stoichiometric chemoselective hydrogenation reaction, which will be important for hydrogen generation and its applications.

Defect engineering of metal oxides is a facile and promising strategy to improve their photocatalytic activity. In the present study, Pt/TiO2-x was prepared by a reduction treatment assisted by hydrogen spillover to pure rutile, anatase, and brookite and was subsequently used for hydrogen production from an aqueous methanol solution. With increasing reduction temperature, the photocatalytic activity of the rutile Pt/TiO2-x increased substantially, whereas the activity of anatase Pt/TiO2-x decreased and that of brookite Pt/TiO2-x was independent of the treatment temperature. Electron-spin resonance analysis revealed that rutile and brookite possess similar defect sites (Ti3+ and concomitant oxygen vacancy) after the reduction at 600 °C, whereas different resonance signals were observed for anatase after the reduction at 600 °C. During the reduction process, electrons donated from spillover hydrogen migrate between the conduction band and the inherent midgap states. This research demonstrates that the depth of the inherent midgap states, depending on the crystal phases, influences the generation of defects, which play a key role in the photocatalytic performance of Pt/TiO2-x.

Efficient transition metal oxide electrocatalysts for the alkaline hydrogen evolution reaction (HER) have received intensive attention to energy conversion but are limited by their sluggish water dissociation and unfavorable hydrogen migration and coupling. Herein, systematic density functional theory (DFT) predicts that on representative NiO, the hydroxylation (OH-) and heterointerface coupled with metallic Cu can respectively reduce the energy barrier of water dissociation and facilitate hydrogen spillover. Motivated by theoretical predictions, we subtly designed a delicate strategy to realize the electrochemical OH- modification in KOH with moderate concentration (HOM-NiO) and to channel rapid hydrogen spillover at the heterointerface of HOM-NiO and Cu, ensuring an enhanced HER kinetic. This HOM-NiO/Cu is systematically investigated by in situ XAS and electrochemical simulations, verifying its extraordinary merits for HER including the enhanced water dissociation, alleviated oxophilicity that is advantageous for consecutive adsorptions of water, and accelerated hydrogen spillover, thereby exhibiting superb HER activity with 33 and 310 mV overpotentials at the current densities of 10 and 1000 mA cm-2 in 1.0 M KOH, outperforming the Pt/C. This study might provide a reasonable strategy for the functionalized design of superior electrocatalysts.

A new variety of CdS/NiO core-shell p-n heterojunction is synthesized by in-situ chemically depositing NiO shell on single-crystal CdS nanorods for the first time. With this method, the range of NiO shell thickness can be accurately controlled within a few nanometers. The optimized CdS/NiO sample (CSN0.5) with a NiO shell layer of 1.5 nm exhibits a highly efficient photocatalytic H2 evolution rate of 731.7 μmol/h (corresponding to 243.9 mmol/g/h) without using co-catalyst, which is among the highest value of all the CdS-based photocatalysts. The apparent quantum efficiency (AQE) of CSN0.5 at 365 nm wavelength reaches 28.19%. The remarkably enhanced photocatalytic performance can be attributed to a hydrogen spillover effect induced by ascorbic acid in CdS/NiO, which promotes the transmission of adsorbed H* from hydrogen-rich NiO (electron-poor region) to hydrogen-poor CdS (electron-rich region) where the adsorbed H* reacts in time with the photogenerated electron to produce H2, facilitating the H2 evolution reaction. This work provides a method to promote the photocatalytic H2 evolution reaction by using hydrogen spillover effect.

Plastics waste has become a major environmental threat, with polyethylene being one of the most produced and hardest to recycle plastics. Hydrogenolysis is potentially the most viable catalytic technology for recycling. Ruthenium (Ru) is one of the most active hydrogenolysis catalysts but yields too much methane. Here we introduce ruthenium supported on tungstated zirconia (Ru-WZr) for hydrogenolysis of low-density polyethylene (LDPE). We show that the Ru-WZr catalysts suppress methane formation and produce a product distribution in the diesel and wax/lubricant base-oil range unattainable by Ru-Zr and other Ru-supported catalysts. Importantly, the enhanced performance is showcased for real-world, single-use LDPE consumables. Reactivity studies combined with characterization and density functional theory calculations reveal that highly dispersed (WO x )n clusters store H as surface hydroxyls by spillover. We correlate this hydrogen storage mechanism with hydrogenation and desorption of long alkyl intermediates that would otherwise undergo further C-C scission to produce methane.

As a hydrogen storage material, palladium nanoparticle decorated nitrogen doped graphene (Pd/N-rGO) has drawn much attention owing to its high absorption capacity at moderate conditions. However, its hydrogen absorption-desorption cycle performance, which is essential for their practical application, has been rarely studied. In this paper, a simple and convenient high temperature thermal reduction method was used to synthesize nitrogen-doped graphene decorated with Pd nanoparticles (Pd/N-rGO). Taken it as a representative, the hydrogen absorption-desorption cycle performance of Pd/N-rGO was investigated. The results showed that after three cycles the hydrogen storage capacity dropped from 2.9 ​wt% to 0.8 ​wt% at 25 ​°C and 4 ​MPa pressure. It was found that the palladium nanoparticles shed from Pd/N-RGO sheet after cycle performance test, and then agglomerated. These phenomena will weaken the hydrogen spillover effect, leading to the decrease of hydrogen storage capacity. Meanwhile, decreased defects reduce the hydrogen absorption sites, which will thus deteriorate the hydrogen storage capacity.

High-entropy alloys (HEAs) have been intensively pursued as potentially advanced materials because of their exceptional properties. However, the facile fabrication of nanometer-sized HEAs over conventional catalyst supports remains challenging, and the design of rational synthetic protocols would permit the development of innovative catalysts with a wide range of potential compositions. Herein, we demonstrate that titanium dioxide (TiO2) is a promising platform for the low-temperature synthesis of supported CoNiCuRuPd HEA nanoparticles (NPs) at 400 °C. This process is driven by the pronounced hydrogen spillover effect on TiO2 in conjunction with coupled proton/electron transfer. The CoNiCuRuPd HEA NPs on TiO2 produced in this work were found to be both active and extremely durable during the CO2 hydrogenation reaction. Characterization by means of various in situ techniques and theoretical calculations elucidated that cocktail effect and sluggish diffusion originating from the synergistic effect obtained by this combination of elements., Facile fabrication of high-entropy alloys (HEAs) nanoparticles (NPs) on conventional catalyst supports remains challenging. Here the authors show TiO2 is a promising platform for the low-temperature synthesis of supported CoNiCuRuPd HEA NPs with excellent activity and durability in CO2 hydrogenation.

The spillover of hydrogen on an inorganic oxide support is studied using DFT calculations. Quantum-chemical calculations for model catalytic sites with structure H(–Al–O–)3(OH)6 and HH+(‒Al–O–)3(OH)6 are performed using the DFT B3LYP/6-31G * energy functional versus electron density with full energy optimization and calculation of the frequencies of normal vibrations. Geometric parameters, electronic characteristics, distribution of electron density, total energies, energies and entropies of transformation, and frequencies of normal vibrations are calculated for the compounds. The geometric structure of molecules and frequencies of normal vibrations are determined using 6-31G* atomic basis sets. The activation energy of hydrogen transfer is determined for these complexes. It is found that an additional positive charge on a catalytic center HH+(–Al–O–)3(OH)6 sharply lowers the activation energy of hydrogen transfer, the value of which is 13.92 kcal/mol. It is shown that the formation of a complex of water with catalytic center HH+(–Al–O–)3(OH)6 further reduces the activation energy of hydrogen transfer to 5.45 kcal/mol, in agreement with the experimental values of the activation energy of spillover hydrogen on aluminum oxide. The mechanism of the hydrogen transfer reaction in a complex of adsorbed water with a charged catalytic center HH+(‒Al–O–)3(OH)6 adequately reflects the mechanism of hydrogen spillover over an inorganic oxide carrier.

In this study, the hydrogen storage capacity of purified multiwalled carbon nanotubes (MWCNTs) was enhanced from 13- to 15-fold at a temperature of 298 K and pressure of 2.0 MPa, upon incorporation of 1.57–1.88 wt% of ultrafine Ti nanoparticles. The effect of a hydrogen spillover Ti catalyst on MWCNTs prepared using the sputtering method was investigated. A comparison between the hydrogen uptake by MWCNTs sputtered with Ti for 3000 s and that for 6000 s was also performed using the Sievert's volumetric apparatus. The significant enhancement in hydrogen uptake was attributed to the interfacial diffusion of hydrogen from Ti to the MWCNTs. The re-adsorption of hydrogen on the pristine MWCNTs and Ti-decorated MWCNTs dehydrogenated at 200 °C indicated that the samples did not compromise their reversible hydrogen uptake during the hydrogenation–dehydrogenation cycles. It was also found that longer exposure of Ti to the MWCNTs during sputtering improved the hydrogen storage capacity. This improvement could be attributed to the presence of a higher amount of Ti deposited on the MWCNTs, as indicated by thermogravimetric analysis study.

The process of hydrogen spillover on metal nanoparticle decorated carbon surfaces has been discussed for many years due to its importance for heterogeneous catalysis and hydrogen storage. The prese...

The Platinum (Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction (HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt. Herein, a molybdenum-doped titanium dioxide (Ti0.9Mo0.1O2) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt. The Ti0.9Mo0.1O2 support can not only tolerate the corrosion environment in the catalytic system, but also generate strong metal-support interaction (SMSI) between the oxide and catalyst. A facile solvothermal method is used to prepare Ti0.9Mo0.1O2 as support to anchor Pt nanoparticles. The 5% Pt supported on Ti0.9Mo0.1O2 catalyst exhibits 4.4-fold mass activity (MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading. The SMSI between the Ti0.9Mo0.1O2 and Pt prevents the Pt aggregation to achieve excellent stability, and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process. This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.

In this work, a new kind of CdS–ZnO core–shell nanorods with controlled ZnO shell are first synthesized by a simple chemical deposition method in aqueous solution. The thickness and distribution of the ZnO shell can be accurately adjusted, and intimate contact interfaces between CdS and ZnO are well constructed. The optimal CSZ0.5 core–shell heterostructure exhibits a photocatalytic H2 evolution rate of 805.5 μmol h−1 without co-catalysts (3 mg of catalyst, equal to 268.5 mmol g−1 h−1), which is 12 and 895 times higher than that of CdS and ZnO, respectively, and is the maximum value among CdS-based photocatalysts under similar experimental conditions. The significant enhancement in the photocatalytic H2 evolution rate can be mainly attributed to three positive factors: the single-crystalline structure of CdS, the Z-scheme mechanism formed between CdS and ZnO, and the introduced ascorbic acid. The first two factors effectively promote the separation and migration of charge carriers, and the latter factor realizes efficient hydrogen spillover for CdS/ZnO to accelerate the photocatalytic hydrogen evolution reaction. In addition, the homogeneous ZnO shell grown on the CdS core efficiently suppresses the photo-corrosion of CdS, which endows CdS/ZnO with outstanding photostability.

The extent of hydrogen spillover on two different Pd-based catalysts supported on mesoporous SBA-15 and MCM-41 is quantitatively predicted using a crystallite-scale model, which considers the effect of size and location of crystallites, metal-support interfacial contact, and diffusivity of the adsorbed species on the support surface. The developed model, in combination with a fixed-bed reactor model predicts that in the absence of any reductant in the feed, the NO conversion is higher ( = 37 %) on the SBA-15 supported catalyst as compared to 25 % on MCM-41, which is consistent with the reported data in the literature. The difference in the catalytic activity is ascribed to the different spillover rates of hydrogen on SBA-15 and MCM-41, which is further correlated to the fraction of Pd crystallites present in the support channels. The model is also used to study the effect of cycle time, H2 concentration, Pd dispersion, and Pd loading on NO reduction under cyclic conditions. Consistent with the literature findings, the model predicts that the Pd surface area and the metal-support interfacial contact increase with an increase in the Pd loading and dispersion, which result in higher spillover and hence increase the NO conversion. Even though the present model has been developed for the H2-SCR system, it can also be extended to other catalytic systems where spillover effects are significant.

It is highly desirable to develop a low-pressure, low-temperature ammonia synthesis process. Although this process is, in principle, thermodynamically feasible under ambient conditions, it remains a big challenge to find ideal catalysts with favorable kinetic pathways. Here, we demonstrate that efficient ammonia synthesis (>3700 μg h−1 gcat.−1) from N2 and H2 gases can proceed at room temperature using Mo, Pt modified TiO2−x under visible light irradiation up to 800 nm. The doped Mo(V) species nearby surface oxygen vacancies (VO) offer coordinatively unsaturated sites for N2 activation with strong adsorption energy and excellent electron back-donation ability. Distinctively, a small amount of surface-loaded Pt nanoparticles trigger hydrogen spillover from Pt to VO, enabling facile NH3 assembly and desorption, as well as increasing free Mo(V) active sites. The incorporation of Mo and Pt also synergistically optimizes the light-harvesting ability and the band structure of TiO2, greatly facilitating the photoexcited N2 reduction and H2 oxidation.

Isolating metal atoms on supports for catalysis has attracted great attention of researchers due to the unique catalytic properties. Here we show by utilizing the hydrogen spillover effect at high temperature (700 °C) that the in situ formed surface oxygen vacancies on TiO2 nanobelts can facilitate the redispersion of Pt nanoparticles to stable single-atoms. The isolated Pt atoms are firmly confined by the surface oxygen vacancy sites in the internal surface of TiO2. Density functional theory (DFT) calculations have further proved that Pt atom is likely to be confined to oxygen vacancies to form single-atom sites. The as-obtained catalyst exhibits excellent photocatalytic water splitting performance with a hydrogen evolution rate of 38.33 mmol mgPt−1 h−1 under simulated solar light irradiation, which is about 59.9 times higher than that of TiO2 nanobelts with Pt nanoparticles. This approach provides a facile method to prepare noble metal catalysts with both high atom economy and reaction activity.

The tungsten oxide nanorods loaded with ruthenium nanoparticles (Ru-WO3) nanocomposite were synthesized by hydrothermal method and impregnation method. The properties of Ru-WO3 catalysts were characterized by various methods, such as BET, XRD, SEM, TEM, EDS and XPS. The results show that hydrogen spillover occurs on the surface of WO3 and the catalytic activity of Ru-WO3 in hydrogenation of cyclohexene increases with the increase of reaction time. Subsequently, the Ru-WO3 catalysts was used to hydrogenate N-propylcarbazole (NPCZ). Compare with commercial 0.5 wt% Ru–Al2O3 catalyst, Ru-WO3 can realize the rapid hydrogen uptake of NPCZ at a lower metal loading (0.34 wt%) and lower temperature (150 °C), which is attributed to the increase of reactive sites caused by hydrogen spillover.

Hydrogen sensing simultaneously endowed with fast response, high sensitivity and selectivity is highly desired in detecting hydrogen leakages such as in hydrogen-driven vehicles and space rockets. Here, hydrogen sensing reined via a hydrogen spillover effect has been developed using palladium nanoparticles photochemically decorated on WO3 nanoparticles (Pd-NPs@WO3-NPs). Theoretically, the Pd-NP catalysts and WO3-NP support are used to construct the hydrogen spillover system, in which Pd NPs possess high catalytic activity, promoting the electron transfer and therefore the reaction kinetics. Beneficially, the Pd-NPs@WO3-NP sensor prototypes toward 500 ppm hydrogen simultaneously exhibit fast response time (∼1.2 s), high response (Ra/Rg = 22 867) and selectivity at a working temperature of 50 °C. Such advanced hydrogen sensing provides an experimental basis for the smart detection of hydrogen leakage in the future hydrogen economy.

A rational porous structure can efficiently enhance the electrode reaction process. In this study, we fabricated a type of three-dimensional (3D)-ordered hierarchically porous carbon via a dual-template method to support ruthenium species as efficient cathodes towards the hydrogen evolution reaction (HER). The ordered hierarchical pores comprised of three levels of porous structure, including the inverse opal-structured macroporous carbon skeleton (ca. 150 nm), the internal-ordered mesoporous structure (ca. 5 nm), and abundant microporous structure (

Local coordination environments of isolated metal atoms in single-atom catalysts (SACs) play decisive roles for their catalytic performance. By varying the morphology and P and N heteroatom doping of the CeO2 support, here we showed that the activity of Pt single atoms on spherical CeO2 is about 7 times higher than that on CeO2 nanorods in hydrogenation of phenylacetylene. Doping the spherical CeO2 support using N is more effective than using P, and could enhance the activity by another 3.3 times, which was 2.6-times even higher than that of spherical CeO2 supported Pt clusters. Diffuse reflectance infrared Fourier transform spectroscopy of chemisorbed CO and X-ray photoelectron spectroscopy showed that N doping induced an increase of the electron density of Pt single atoms, opposite to the effect of P doping. H–D exchange and temperature-programmed reduction of hydrogen revealed that a large enhancement of hydrogen dissociation activity and hydrogen spillover by N doping are both essential for promoting the activity for catalytic hydrogenation.

Photoelectrochemical N2 reduction reaction (PEC NRR) is a promising method to solve the problems of environmental protection and energy sustainability. However, the strong chemical stability of the N≡N bond and competitive hydrogen evolution reaction (HER) cause the nonideal efficiency of N2 → NH3 conversion in actual operation. For the first time, a Mo2C/C heterostructure was fabricated as a PEC cathode for N2 reduction under environmental conditions. The Mo2C/C heterostructure could effectively decrease the coverage of hydrogen spillover and inhibit the competitive HER, resulting in a desirable selectivity for N2 activation. Meanwhile, the decoration of the C shell further promoted the stability and conductivity of Mo2C. Mo sites of Mo2C were considered as activation centers, which played a dominant role in the final PEC performance. An optimal NH3 yield rate of up to 6.6 μg h-1 mg-1 was achieved with the Mo2C/C heterostructure, which was almost 3 times that with pristine C. The faradic efficiency (FE) of the Mo2C/C heterostructure was 37.2% at 0.2 V (vs Ag/AgCl). This work not only provides an insight into the interplay between the Mo2C/C heterostructure and N2 activation, but also reveals its great potential in NH3 synthesis by a green route.

Summary Ideal heterogeneous metal hydrogenation catalysts are featured by simultaneously high activity, selectivity, and stability. Herein, we report a general yet powerful strategy to design and fabricate dual-active-sites Co@C core-shell nanoparticle for boosting selective hydrogenation of various N-heteroarenes. It can break the limitation of scaling relation on traditional metal surfaces, and thus afford unprecedentedly high selectivity, activity, and stability. Combining kinetics analysis and DFT calculations with multiple techniques directly unveil that the critical porous carbon shell with a pore size of 0.53 nm not only allows H2 diffusion to Co sites for activation and blocks accessibility of N-heteroarenes but also catalyzes hydrogenation of N-heteroarenes via hydrogen spillover from Co sites. In addition, the presence of surface/subsurface carbon at the Co sites shows high anti-sulfur poisoning and anti-oxidant capability. This work is valuable for guiding the design and manipulation of cost-effective and robust hydrogenation catalysts.

Ni–La2O3 cermet hydrogen electrode having almost no ionic conductivity still exhibits excellent electrochemical performance owing to the hydrogen spillover process from high hydrogen adsorption capability on the La2O3 surface. In this work, we develop Ni–La2O3 cermet hydrogen electrode originating from the in-situ decomposition of the La2NiO4+δ(LNO) oxide, and then perform the electrochemical properties for quasi-symmetrical solid oxide fuel cells (Q-SSOFCs), which own YSZ electrolyte support wrapped GDC barrier layer. The area specific resistance (ASR) of LNO air electrode increases from 2.09 to 7.41 Ω cm2, with the temperature of decreasing from 800 to 600 °C. The electrochemical performances of Q-SSOFCs with Ni–La2O3 cermet hydrogen electrode and LNO air electrode are characterized, and the values of the peak power density and the electrode polarization resistance (Rp) of the symmetrical electrodes measured at 800 °C are 245.18 mW cm−2 and 0.61 Ω cm2. These results indicate that the hydrogen spillover process of Ni–La2O3 cermet hydrogen electrode can greatly promote the hydrogen oxidation reaction.

High-performance electrocatalysts for the hydrogen evolution reaction (HER) have an important role to play in the development of renewable energy. Despite the enormous efforts to find cheaper alternative materials, platinum remains the most efficient known HER electrocatalyst. Therefore, it is necessary to find ways to maximize Pt utilization in actual practical applications. Here we demonstrate a facile strategy for synthesizing RuCeO x -supported selectively loaded atomic Pt (0.49 wt.%) (denoted Pt/RuCeO x -PA) by photoactivation at ambient temperature and pressure. Due to the photoelectron transfer at the Mott-Schottky heterojunction in RuCeO x , Pt atoms became directionally embedded into the RuO 2 lattice. The resulting selectively loaded Pt-O-Ru moieties in Pt/RuCeO x -PA exhibit a stronger hydrogen spillover effect than Pt complexes randomly loaded by either chemical activation or thermal activation. As a result, Pt/RuCeO x -PA shows superior HER performance to the materials prepared by random loading and is even better than a commercial Pt/C catalyst with much higher Pt loading (20 wt.%) at high current densities (from 50-600 mA cm -2 ). The selective loading strategy employed in our work not only provides an effective approach for constructing controllable active sites in HER catalysts but should also be applicable in the fabrication of other atomic catalysts.

Hydrogen storage by spillover in porous carbon material (PCM) has achieved great success in experiments. During the past 20 years, a large number of theoretical works have been performed to explore the hydrogen spillover mechanism, look for high-performance hydrogen storage materials and high-efficiency catalysts. In this paper, we summarize and analyze the results of the past researches, and draw the following conclusions: (1) In PCM surface, the stability of chemisorbed H can be reached through phase nucleation process, which can be initiated in the vicinity of surface impurities or defects. (2) To achieve the 2020 U.S. Department of Energy (DOE) target, the PCM material used for hydrogen storage by spillover should have a sp2 carbon ratio greater than 0.43 and a surface area less than 3500 m2/g, which gives us an inspiration for exploring hydrogen spillover materials. (3) Due to a high barrier, the hydrogen spillover almost can not be initiated on pure PCM substrate at room temperature. By introducing the defects or impurities (e.g. holes, carbon bridges, oxygen functional groups, boron atoms and fluorine atoms), the spillover barriers can be reduced to a reasonable range. In addition, hydrogen atoms may also migrate in a gas phase. (4) According to our previous results of kinetic Monte Carlo simulations, there is a linear relationship between the reaction temperature and the migration barrier. The optimal barrier for the hydrogen spillover should be in the range of 0.60–0.88 eV. (5) Once the hydrogen atoms are chemically adsorbed on the carbon substrate, it is difficult to diffuse again due to the strong strength of C–H bond. Several theoretical diffusion mechanisms have been proposed. For example, the H atoms in physisorption state can diffuse freely on carbon surfaces with high mobility, using the shuttle gases (e.g. BH−4, H2O, HF and NH3) to make the migration thermodynamically possible and decrease the migration barrier, the H atoms diffuse inside the interlayer space of the bi- and tetralayer graphene, and introducing the impurities on the surface to facilitate the hydrogen diffusion. (6) The H desorption through the directly recombination or the reverse spillover is unlikely to occur at normal temperature. The Eley-Rideal reaction may be the only possible mechanism for desorption of the adsorbed H atoms in carbon substrate. Finally, we have made a prospect for further research works on hydrogen storage by spillover.

Tuning CO2 hydrogenation selectivity to obtain targeted value-added chemicals and fuels has attracted great yet everincreasing attention. How ever, a fundamental understanding of the nature to control the selectivity is still lacking, posing a challenge in catalyst design and development. Here, w e report our new discovery in ambient pressure CO2 hydrogenation reaction where selectivity canbe completely reversed by simply changing the crystal phases of TiO2 support (anatase- or rutile-TiO2) or changing metal loadings on anatase-TiO2. Operando spectroscopy and NAP-XPS studies reveal the determining factor is dif ferent electron transfer from metal to support under reaction conditions most probably as a result of the different extents of hydrogen spillover, which changes the adsorption and activation of the intermediate of CO. Based on this new finding, we can not only regulate CO2 hydrogenation selectivity but also tune catalytic performance in other important reactions, thus opening up a door for efficient catalyst development by rational design. Fil: Li, Xiaoyu. University Of Chinese Academy Of Sciences; China. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Lin, Jian. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Li, Lin. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Huang, Yike. University Of Chinese Academy Of Sciences; China. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Pan, Xiaoli. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Collins, Sebastián Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Ren, Yujing. University Of Chinese Academy Of Sciences; China. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Su, Yang. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Kang, Leilei. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Liu, Xiaoyan. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Zhou, Yanliang. University Of Chinese Academy Of Sciences; China. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Wang, Hua. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Wang, Aiqin. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Qiao, Botao. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Wang, Xiaodong. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China Fil: Zhang, Tao. Dalian Institute Of Chemical Physics Chinese Academy Of Sciences; China

Interactions between the active components with the support are one of the fundamentally factors in determining the catalytic performance of a catalyst. In contrast to the comprehensive understanding on the strong metal-support interactions (SMSI) in metal-based catalysts, it remains unclear for the interactions among different oxides in mixed oxide catalysts due to its complexity. In this study, we investigated the interaction between CeO2 and LaFeO3, the two important oxygen storage materials in catalysis area, by tuning the sizes of CeO2 particles and highlight a two-fold effect of the strong oxide-oxide interaction in determining the catalytic activity and selectivity for preferential CO oxidation in hydrogen feeds. It is found that the anchoring of ultra-fine CeO2 particles (

The hydrogen spillover effect (HSPE) on metal catalysts supported on non-reducible oxides is still controversial. Our investigation shows that the controversy comes from a misunderstanding about st...

In this work, the NiCu solid solutions with different Ni/Cu molar ratios were prepared and then doped into MgH2 through ball milling to modify its hydrogen sorption properties. The experimental results show that the Ni–25%Cu and Ni–50%Cu exhibit the superior catalytic effect over pure Ni, pure Cu and Ni–75%Cu on the dehydrogenation of MgH2. Among them, the 5h-milled MgH2/Ni–50%Cu system starts to desorb hydrogen at 205.8 °C, which is about 96.9 °C lower than that of as-milled pristine MgH2. Moreover, the MgH2/Ni-50% Cu system can release 5.14 wt% hydrogen at 300 °C within 15 min, while MgH2 can only release 2.92 wt% hydrogen under the same condition. More importantly, the dehydrogenated MgH2/Ni–50%Cu can reabsorb 4.37 wt% hydrogen even at 250 °C for 30 min. The enhanced hydrogen sorption kinetics of MgH2/Ni–50%Cu mainly attributes to the “hydrogen spillover” effect of in-situ formed Mg2Ni(Cu) phases. Further theoretical calculations reveal that the strong interactions between H and Ni/Cu result in the weakened stability of MgH2, decreased bond strength of Mg–H and enhanced dehydrogenation properties of MgH2. This research provides an important guidance for design multiple transition metals catalysts to improve efficiently hydrogen storage properties of magnesium-based and other metal-based hydrides.

The spillover of hydrogen species and its role in tuning the activity and selectivity in catalytic hydrogenation have been investigated in situ using surface-enhanced Raman spectroscopy (SERS) with 10 nm spatial resolution through the precise fabrication of Au/TiO2 /Pt sandwich nanostructures. In situ SERS study reveals that hydrogen species can efficiently spillover at Pt-TiO2 -Au interfaces, and the ultimate spillover distance on TiO2 is about 50 nm. Combining kinetic isotope experiments and density functional theory calculations, it is found that the hydrogen spillover proceeds via the water-assisted cleavage and formation of surface hydrogen-oxygen bond. More importantly, the selectivity in the hydrogenation of the nitro or isocyanide group is manipulated by controlling the hydrogen spillover. This work provides molecular insights to deepen the understanding of hydrogen activation and boosts the design of active and selective catalysts for hydrogenation.

This work demonstrated the use of TiO2 as a promising platform for the synthesis of non-equilibrium RhCu binary alloy nanoparticles (NPs). These metals are regarded as immiscible based on their phase diagram but form NPs with the aid of the significant hydrogen spillover on TiO2 with concurrent proton–electron transfer. The resulting RhCu/TiO2 exhibited 2.6 times higher catalytic activity than Rh/TiO2 during hydrogen production from the hydrolysis of ammonia borane (AB), due to a synergistic effect. Theoretical simulations showed a higher energy value for the adsorption of AB on the RhCu alloy and a lower activation energy for the rate determining N–B bond dissociation by the attack of H2O during AB hydrolysis compared to monometallic Rh. High-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed the formation of RhCu alloy NPs with a mean diameter of 2.0 nm on the TiO2. H2-temperature programmed reduction and in situ X-ray absorption fine structure analyses at elevated temperature under H2 demonstrated that Rh3+ and Cu2+ precursors were simultaneously reduced only on the TiO2 support. This effect resulted from the improved and limited reducibility of Cu2+ and Rh3+, respectively. The rate of hydrogen spillover of TiO2 is faster as compared to γ-Al2O3 and MgO as evidenced by sequential H2/D2 exchanges during in situ Fourier transform infrared analyses. Density functional theory calculations also showed that the migration of H atoms on TiO2 proceeds with a lower energy barrier than that on Al2O3, and the reduction of Cu2+ species is facilitated by H spillover on the support rather than by direct reduction by H2. These results confirm the vital role of TiO2 in the formation of the alloy and may represent a new strategy for the synthesis of different non-equilibrium solid solution alloys., This work demonstrates the use of TiO2 as a promising platform for the synthesis of non-equilibrium binary solid solution alloy nanoparticles with a combination of immiscible Rh and Cu assisted by the hydrogen spillover.

Cerium zirconium-based (CZ) oxygen storage materials (OSMs) play a crucial role in three-way catalysts (TWCs), while CZ needs to be modified to satisfy more rigorous emission standard. In this study, transition metal (TMs = Mn, Cr, Fe, Cu) oxides modified CZ were prepared by incipient wetness impregnation method to improve the oxygen storage capacity of CZ-based materials. To clearly illustrate the influence of TM oxides, N2 adsorption-desorption, X-ray diffraction (XRD), oxygen storage capacity (OSC), temperature programmed reduction by H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the physical and chemical properties of samples. It is found that, all modified CZ have higher OSC, lower reduction temperatures than those of pristine CZ. Interaction between TMOs and CZ take precedence over specific surface to influence OSC. Notably, FeOx/CZ has the highest OSC, which is about 1.9 times that of CZ and it could be attributed to synergistic effect between FeOx and CZ; CuOx/CZ has the lowest reduction temperature which is 168°C lower than that of CZ, and it can be explained by hydrogen spillover effect.

In this study, we demonstrate sustainable and green nanotechnology for room-temperature synthesis of H$_x$WO$_3$ ($0

Subnanometric metal particles, the so-called “clusters”, are known to be responsive to their surroundings, but the detection of occurring changes, understanding the causes, and predicting the consequences are still extremely difficult for such small particles. Our study was aimed at estimating the potential of adsorption-based methods for these purposes. Using carbon monoxide as a probing molecule, which readily adsorbs on both bare and H-covered Pt surface, we have probed the adsorption properties of highly dispersed Pt/γ-Al2O3 samples after treatments under different atmospheres and temperatures (H2 or inert gas, 25–500 °C). The combined results of CO-chemisorption measurements, CO TPD, CO TPO, H2-by-CO displacement, and H2 TPD suggest that the system shuttles between two states: one with oxygen vacancies in the support and the other one with redox-active oxygen near the Pt clusters. These extreme states can be reversibly created and deleted, giving rise to innumerable intermediate structures that differ in the amount, binding strength, and/or reactivity of adsorbed species. Two adsorbates could act cooperatively, resulting in hydrogen spillover onto the support and making the adsorbate–metal–support interactions even more complex. Implications for better understanding the dynamic behavior of oxide-supported clusters and nanoparticles are discussed.

Catalytic CO2 reduction to fuels and chemicals is a major pursuit in reducing greenhouse gas emissions. One approach utilizes the reverse water-gas shift reaction, followed by Fischer-Tropsch synthesis, and iron is a well-known candidate for this process. Some attempts have been made to modify and improve its reactivity, but resulted in limited success. Now, using ruthenium-iron oxide colloidal heterodimers, close contact between the two phases promotes the reduction of iron oxide via a proximal hydrogen spillover effect, leading to the formation of ruthenium-iron core-shell structures active for the reaction at significantly lower temperatures than in bare iron catalysts. Furthermore, by engineering the iron oxide shell thickness, a fourfold increase in hydrocarbon yield is achieved compared to the heterodimers. This work shows how rational design of colloidal heterostructures can result in materials with significantly improved catalytic performance in CO2 conversion processes.

A comparative study of the hydrogen spillover phenomenon on pristine graphene and anatase (101)-supported Pt4 catalysts has been carried out by using density functional theory with Hubbard correcti...

Selective catalytic hydrogenation of substituted nitro compounds (NCs) of hydrophobic nature in aqueous solution using transition-metal-based catalysts is highly desirable yet fairly challenging. Herein, we propose the idea of amphiphilic mesoporous catalysts for selective hydrogenation of hydrophobic NCs in aqueous solution. The amphiphilic catalyst Co@Co-N-C@SBA-15 with a sandwich-like structure is constructed by a one-step solvent-free melting coating method. The catalyst has an external hydrophilic silica support that facilitates catalyst dispersion in water. It has unique Co-N-C catalytic layers uniformly coated in the inner mesopore surfaces of the silica support, which enhance the selective adsorption and activation of hydrophobic NCs. It has a high surface area (448.2 m2/g) and a uniform mesopore size (∼7.0 nm) for fast mass transportation. It possesses ultrafine metallic Co nanoparticles uniformly anchored within the N-doped carbon (N-C) layers for easy magnetic separation. These features make the catalyst excellent for the selective hydrogenation of 4-nitrostyrene to form 4-aminostyrene, with a high conversion of 98.0% in 1.0 h, a superior selectivity of 98.8%, and a good stability under mild conditions. A comprehensive study confirms the excellence of the amphiphilic mesoporous catalysts compared with other control catalysts. The Co-N sites are the intrinsic active sites. They can selectively adsorb and activate the nitro groups other than the vinyl groups, leading to superior selectivity. Water as the solvent results in the best performance compared with typical organic solvents probably because of an enhanced water-mediated hydrogen spillover and transfer.

Single-atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single-atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO3-x (Pt NP/WO3-x ). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO3-x (Pt SA/WO3-x ). The Pt SA/WO3-x exhibited a higher degree of hydrogen spillover from Pt atoms to WO3-x at the interface, compared with Pt NP/WO3-x , which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.

Hydrogen adsorption and desorption over Ru/SiO2 and Ru/Vulcan are investigated in terms of hydrogen storage and release characteristics by both dynamic and static experiments. Ru particle dispersions as a function of metal loading were determined by HR-TEM and volumetric chemisorption experiments. Vulcan was more accommodating for spillover hydrogen than SiO2. High Ru dispersions, i.e., small particle sizes, favored the amount of hydrogen spillover to Vulcan, as revealed by temperature programmed desorption (TPD) of hydrogen. TPD of hydrogen under He flow experiments over Ru/SiO2 and Ru/Vulcan materials revealed a low temperature process (up to 200 °C) attributed to desorption of weakly bound hydrogen from Ru metal surface. A high temperature process (above 450 °C) was attributed to diffusion of hydrogen from the support to the Ru particle and desorption at the Ru sites. Hydrogen adsorbs strongly on Ru metal, as indicated by the initial heats of H2 adsorption measured as 100 kJ/mol over 1 wt% Ru/Vulcan by adsorption calorimetry. At higher coverages, heat of adsorption of hydrogen was measured as 10 kJ/mol. Low heat of adsorption of hydrogen at high coverages indicate multilayer weak adsorption of hydrogen over the storage material, which can desorb at lower temperatures.

In this work, multiwalled carbon nanotubes (MWCNTs) promoted Co–B catalysts for NaBH4 hydrolysis have been designed and synthesized. The structural features of as-prepared catalysts have been investigated and discussed as a function of MWCNTs contents by X-ray diffraction, X-ray photoelectron spectra, N2 adsorption/desorption isotherms, scanning electron microscope. The results show that the catalysts still maintain an amorphous structure with the addition of carbon nanotubes promoter. However, the appropriate amount of MWCNTs promoter in Co–B catalysts leads to large specific surface area, fine dispersion of active components, increased active sites and high electron density at active sites. Moreover, hydrogen spillover on the catalyst is promoted, which contributes to regeneration of active sites and accelerating catalytic cycle. Among all the experimental samples, it is found that the Co–B catalyst promoted by 10 wt% carbon nanotubes exhibits optimal catalytic activity with remarkably high hydrogen generation rate of 12.00 L min−1·gcatalyst−1 and relatively good stability.

Hydrogen production by steam reforming of ethylene glycol (EG) at 300 °C was investigated over SiO2 and CeO2 supported Pt–Ni bimetallic catalysts prepared by incipient wetness impregnation methods. It was observed that impregnation sequence of Pt and Ni can affect the performance of catalysts apparently. Catalyst with Pt first and then Ni addition showed higher EG conversion and H2 yield owing to the Ni enrichment on the surface and the proper interaction between Pt and Ni. It was observed that although SiO2 supported catalysts exhibited better activity and H2 selectivity, CeO2 supported ones had better stability. This is attributed to the less coke formation on CeO2. Increasing Pt/Ni ratio enhanced the reaction activity, and Pt3–Ni7 catalysts with 3 wt% Pt and 7 wt% Ni showed the highest activity and stability. Ni surficial enrichment facilitated the C—C bond rupture and water gas shift reactions; and Pt addition inhibited methanation reaction. Electron transfer and hydrogen spillover from Pt to Ni suppressed carbon deposition. These combined effects lead to the excellent performance of Pt3–Ni7 supported catalysts. Keywords: Ethylene glycol, Steam reforming, Pt–Ni bimetallic catalyst, Hydrogen production, Synergistic effect

A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu: Pd atomic ratios were prepared by conventionally sequential impregnation (CSI) and modified sequential impregnation (MSI) of Cu and Pd for selective hydrogenation of acetylene. Characterization indicates that the supported copper (II) nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO3)2 crystals. In addition, for the catalysts prepared by MSI, Pd atoms can form PdCu alloy on the surface of metal particles, however, for the catalysts prepared by CSI, Pd tends to migrate and exist below the surface layer of Cu. Reaction results indicate that compared with CSI, the MSI method enables samples to possess preferable stability as well as comparable reaction activity. This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles. Moreover, even Pd loading is super low, < 0.045 wt-% in this study, by through adjusting Cu loading to an appropriate value, attractive reactivity and selectivity still can be achieved.

How to reduce the H migration barrier in hydrogen spillover is one of the crucial points for hydrogen storage. In this study, we use COF-8 as a representative to study the effect of F decoration fo...

MgH $_2$ is a promising and popular hydrogen storage material. In this work, the hydrogen desorption reactions of a single Pd atom adsorbed MgH $_2$ (110) surface are investigated by using first-principles density functional theory calculations. We find that a single Pd atom adsorbed on the MgH $_2$ (110) surface can significantly lower the energy barrier of the hydrogen desorption reactions from 1.802 eV for pure MgH $_2$ (110) surface to 1.154 eV for Pd adsorbed MgH $_2$ (110) surface, indicating a strong Pd single-atom catalytic effect on the hydrogen desorption reactions. Furthermore, the Pd single-atom catalysis significantly reduces the hydrogen desorption temperature from 573 K to 367 K, which makes the hydrogen desorption reactions occur more easily and quickly on the MgH $_2$ (110) surface. We also discuss the microscopic process of the hydrogen desorption reactions through the reverse process of hydrogen spillover mechanism on the MgH $_2$ (110) surface. This study shows that Pd/MgH $_2$ thin films can be used as good hydrogen storage materials in future experiments.

A zirconia supported nickel catalyst for CO2 methanation has been prepared via a rapid and effective plasma decomposition of nickel precursor at atmospheric pressure and temperature around 150 °C, followed by hydrogen reduction at 500 °C. The obtained Ni/ZrO2 catalyst shows high Ni dispersion with principally exposed Ni(111) lattice plane. An enhanced cooperation between Ni and interfacial active sites is achieved as well, which leads to rapid dissociative adsorption of H2 and hydrogen spillover. Sufficient H atoms are thereby generated for CO2 hydrogenation and helpful to create oxygen vacancies on the ZrO2 surface. Higher basicity correlated to the oxygen vacancies further enhances CO2 adsorption and activation. Hence, a superior low temperature activity for CO2 methanation was achieved. For example, a CO2 conversion of 71.9% with a CH4 yield of 69.5% was achieved over the plasma decomposed catalyst at 300 °C with a feeding gas consisting of H2 (32 ml min−1), CO2 (8 ml min−1) and N2 (10 ml min−1) at a GHSV of 60,000 h-1. The corresponding TOF value towards CO2 conversion is 0.61 s-1. However, the CO2 conversion, CH4 yield and TOF value are only 32.9%, 30.3% and 0.39 s-1 at the same reaction conditions over the thermally prepared catalyst. The operando DRIFT analyses demonstrate that CO2 methanation over the plasma decomposed catalyst follows the CO-hydrogenation route. The exposed high-coordinate Ni(111) facets of the plasma decomposed catalyst facilitate the decomposition of CO2 and formates into adsorbed CO. The subsequent hydrogenation of adsorbed CO leads to the production of methane. However, the thermally decomposed catalyst with complex Ni crystal structure and more defects mainly takes the pathway of direct formate hydrogenation. The present study confirms the structure of Ni/ZrO2 has significant effect on the catalytic activity for CO2 methanation.