Electronic Metal-support Interactions Research Articles

Modulating the Electronic Metal-Support Interactions to Anti-Leaching Pt Single Atoms for Efficient Hydrosilylation.

Modulating the electronic metal-support interaction (EMSI) of the single-atomic sites against leaching via microenvironment regulation is critical to achieving high activity and stability but remains challenging. Herein, this work selectively confines Pt single atoms on CoFe layered double hydroxide (LDH) by three oxygen atoms around cation vacancy (Pt1 /LDHV ) or one oxygen atom at the regular surface (Pt1 /LDH) via cation vacancy engineering. By characterizing the structural evolution of the obtained catalysts before and after vacancy construction and single-atom anchoring, this work demonstrates how the microenvironments modulate the EMSI and the catalytic performance. Theoretical simulations further reveal a significantly enhanced EMSI effect by the three-coordinated Pt1 atoms on cation vacancies in Pt1 /LDHV , which endows a more prominent anti-leaching feature than the one-coordinated ones on the regular surface. As a result, the Pt1 /LDHV catalyst shows exceptional performance in anti-Markovnikov alkene hydrosilylation, with a turnover frequency of 1.3×105 h-1 . More importantly, the enhanced EMSI of Pt1 /LDHV effectively prevented the leaching of Pt atom from the catalyst surface and can be recycled at least ten times with only a 3.4% loss of catalytic efficiency with minimal Pt leaching, and reach a high turnover number of 1.0×106 .

Shape dependency of CO2 hydrogenation on ceria supported singly dispersed Ru catalysts

Harnessing the selectivity in catalytic hydrogenation of CO2 is important for producing valuable chemicals. Herein, the shape dependency of the CO2 hydrogenation on singly dispersed Ru/CeO2 catalysts is investigated. CeO2 of three shapes, including nanocube, nanooctahedron and nanorod, are prepared as the catalyst supports and assigned to the surface of (100), (111) and (110) crystal plane, respectively. The Ru/CeO2 (nanorod) exhibits the highest selectivity to CO (97.6 %) at 350 °C, while the Ru/CeO2 (nanocube) exhibits a mediocre selectivity to CO (41.4 %) but the highest CO2 conversion. The shape of the CeO2 support determines the electronic state of supported Ru atoms through the electronic metal-support interaction. The low CO affinity on cationic Ruβ sites leads to the higher selectivity to CO on the Ru/CeO2 (nanorod) and Ru/CeO2 (nanooctahedron) catalysts, while the strong dissociation ability of H2 on low valence Ruα sites results in the high activity on the Ru/CeO2 (nanocube) catalyst.

Modulating electronic Metal–Support interactions of Pt-CuO/CeO2 catalyst via quenching to optimize catalytic activity

Pt-based catalysts are one of the most extensively used heterogeneous catalysts for the degradation of pollutants, and regulating electron-metal-support interaction (EMSI) is an efficient strategy to enhance the performance of Pt-based catalysts. Herein, we introduced a quenching technique for regulating the EMSI of Pt-CuO/CeO2 catalysts to significantly boost its CO catalytic activity. The EMSI optimized by quenching was determined to promote the electron redistribution between Pt and CuO/CeO2 via Cu–O-Pt structure, thus forming more electron-rich Pt species and enhancing the surface oxygen species activity. From comprehensive characterization investigations, we confirmed that the superior activity arouse from the moderate Pt0/Pt2+ ratio, in which CO molecules were preferentially adsorbed on the electron-rich Pt sites and reacted with active oxygen species from PtOx or CuO/CeO2, accelerating the whole CO catalytic process. Our finding provided a new inspiration to control EMSI of Pt-based catalysts and widened the application of quenching chemistry in heterogeneous catalysis.

Silver-induced adsorption optimization of adjacent Co tetrahedral sites for enhanced oxygen reduction/evolution reaction

Physical structure change of catalysts based on the electronic metal-support interaction (EMSI) effects is a prospective strategy to regulate the surface electronic structure of catalysts and further enhance their catalytic performance. To optimize the constrained intrinsic oxygen evolution reaction/oxygen reduction reaction (OER/ORR) activity of spinel MnCo2O4, we present a facile hydrothermal and photoreduction strategy to synthesize the Ag and MnCo2O4 supported on N-doped carbon nanotubes (Ag-MnCoO/NCNTs) with the EMSI effect. Ag-MnCoO/NCNTs as catalyst shows enhanced performance for OER (overpotential of 340 mV) and ORR (half-wave potential of 0.80 V). Furthermore, a zinc-air battery is assembled based on Ag-MnCoO/NCNTs cathode, which affords an open circuit potential of 1.49 V and favorable cycling performance for 200 h. Theoretical calculations illustrate the introduction of Ag reduces the charge density of the tetrahedral Co site along the direction of the dangling bonds and optimizes the adsorption of oxygen intermediates on tetrahedral Co, thus lowering the reaction activation energy and improving its oxygen catalytic activity. This work provides new insights to guide the fabrication of advanced oxygen electrocatalysts.

Architecture of urchin-like TiO2 integrated ultrasmall Rh nanoparticles with oxygen vacancy-reinforced electronic metal-support interaction for boosting hydrogen production from ammonia borane hydrolysis

Metal oxide-supported Rh nanoparticles (NPs) can provide abundant catalytically active sites for hydrogen evolution from ammonia borane hydrolysis (ABH). Considering the scarcity and high cost, developing effective strategies to reduce the utilization of Rh and simultaneously improving its catalytic activity is absolutely needed. Here, we develop ultrafine Rh NPs anchored on oxygen vacancies (VO)-bearing urchin-like TiO2 (U-TiO2). VO can facilitate the formation of electron-rich metallic Rh surface and boost the H2O dissociation, leading to highly efficient hydrogen generation from ABH without alkali promoters. Noticeably, the temperature-controlled annealing of the Rh/U-TiO2 precursor at 450 °C in reducing atmosphere generates the maximum VO concentration. This arouses strong electronic metal-support interaction between the Vo and Rh NPs to yield electron-rich metallic Rh surface. The obtained Rh/UT-450Vo exhibits a high initial turnover frequency of 1729 min−1 for ABH without alkali promoters, outperforming that of the contrast samples and most of previously developed Rh catalysts. This finding offers an effective strategy to fabricate high-efficiency metal oxide-supported metal NPs toward catalytic hydrogen production.

Differences in N species induced by pyrolysis temperature: D-band center adjustment over the biomass carbon-supported CoP for boosting hydrogen evolution reaction

Nitrogen (N) species in biomass-based carbon can be adjusted through pyrolysis at different temperatures, optimizing the valence band structure of supported metal nanoparticles through electronic metal-support interactions (EMSIs). Herein, ginkgo leaves-based carbon supported cobalt phosphide (CoP@NSPC-T, T = 850, 900 and 950 °C) was obtained via carbothermal reduction method at different pyrolysis temperature. Pyridinic N and pyrrolic N in carbon lattice were dramatically decreased with pyrolysis temperature raised, whereas the graphitic N showed the opposite trend. The change in N species (pyridinic N, pyrrolic N and graphitic N) reconfigured the valence band structure of CoP@NSPC-T, inducing the enhancement of work function and the upshift of d-band center. A relationship between the ratio of (pyridinic N + pyrrolic N)/graphitic N, work function, d-band center, and HER activity (η10) of catalysts was established. CoP@NSPC-900 with a moderate work function value and d-band center tend to achieve a balance for Volmer process and Heyrovsky process, exhibiting the lowest η10 value activity among the resulted catalysts as the ratio of (pyridinic N + pyrrolic N)/graphitic N is 1.33.

Local environmental engineering for highly stable single-atom Pt1/CeO2 catalysts: first-principles insights

Single-atom Pt1/CeO2 catalysts may cope with the high cost and durability issues of fuel cell electrocatalysts. In the present study, the stability and underlying interaction mechanisms of the Pt1/CeO2 system are systematically investigated using first-principles calculations. The Pt adsorption energy on CeO2 surfaces can be divided into chemical interaction and surface deformation parts. The interaction energy, mainly associated with the local chemical environment, i.e. the number of Pt-O bonds, plays a major role in Pt1/CeO2 stability. When forming a Pt-4O configuration, the catalytic system has the highest stability and Pt is oxidized to Pt2+. An electronic metal-support interaction mechanism is proposed for understanding Pt1/CeO2 stability. In addition, our calculations show that the Pt1/CeO2(100) system is dynamically stable, and the external O environment can promote the further oxidation of Pt to Pt n+ (2 ≤ n < 4). The present study provides useful guidance for the experimental development of highly stable and efficient electrocatalysts for fuel cell applications.

Construction of anchoring traps-reinforced ultrafine ruthenium nanoparticles as efficient catalysts for boosting H2 production from ammonia-borane hydrolysis

Hydrogen release through ammonia-borane hydrolysis (ABH) is vital for mitigating the energy crises and environmental problems from fossil fuels. However, improving the catalytic performance for ABH via concomitantly regulating the atom utilization efficiency and electronic metal-support interaction of supported catalysts remains challenging. Herein, anchoring traps-reinforced nano-ruthenium integrated hollow N-doped carbon spheres (Ru@HNCS) are synthesized and utilized for ABH toward hydrogen production. The synergy of void trapping and N-anchoring effects enables the fabrication and uniform distribution of ultrafine Ru (1.47 nm in diameter) nanoparticles (NPs) onto the HNCS matrix. Compared with the Ru@C analogue, the achieved Ru@HNCS exhibits much higher catalytic activity (turnover frequency: 1051 min−1), lower activation energy (26.9 kJ mol−1) and higher reusability toward hydrogen production from ABH. The high atomic utilization efficiency of metal species and electronic metal-support interaction can effectively accelerate the oxidative cleavage of the H–O bonds in the attacked H2O, thus kinetically boosting catalytic performance for ABH. The present study represents a useful strategy to fabricate efficient supported nanocatalysts for catalytic applications.

Electronic Metal‐Support Interactions in Atomically Dispersed Fe(III)‐VO2 Nanoribbons for High‐Performance Lithium–Sulfur Batteries

AbstractLithium–sulfur (Li–S) batteries have attracted wide attention as high‐energy‐density energy storage devices, but their practical applications are hindered by the severe shuttle effect and sluggish kinetics of lithium polysulfides (LiPSs). To address these challenges, polar mediators are employed to chemisorb and catalyze LiPSs, but most of them suffer from low electronic conductivity and poor catalytic activity. Here, a novel strategy is reported to enhance both properties by dispersing Fe(III) atoms in VO2 nanoribbons(Fe‐VO2), creating electronic metal‐support interactions (EMSI) that modulate the electronic structure and charge transfer of VO2. Theoretical calculations reveal that EMSI lowers the energy barrier for the decomposition of Li2S from 1.60 to 1.32 eV and increases the electronic conductivity of VO2. Fe doping reduces the Li‐ions diffusion barrier from 1.42 eV in VO2 to 0.99 eV in Fe‐VO2. The Fe‐VO2 catalyst shows strong adsorption and fast converstion of LiPSs, resulting in high energy density and long cycling life of Li‐S batteries. The cathode with Fe‐VO2 maintains a higher capacity retention of 67% after 500 cycles at 1 C, compared with 52.4% and 53.6% for the carbon black based cathode and VO2 based cathode, respectively. This work demonstrates the potential of EMSI for designing efficient catalysts for Li–S batteries and provides new insights into the electronic structure engineering of polar mediators.

Electron donation promotes the dual activation of lattice oxygen and molecular oxygen: The Pt-Pd/CeO2 catalyst efficiently catalyzes toluene

Dual activation of molecular and lattice oxygen is an important step in the catalytic oxidation of volatile organic compounds. Herein, CeO2 was derived from MOF as an electron donor support to develop a co-catalyst with Pt-Pd alloy nanoparticles (Pt-Pd/CeO2). The Prepared Pt-Pd/CeO2 exhibits excellent catalytic activity towards toluene oxidation, showing a turnover frequency (TOF 0.26 s−1) higher than those of Pt/CeO2 (0.05 s−1) and Pd/CeO2 (0.02 s−1). Several in situ experimental techniques and density functional theory calculations have revealed that the introduction of Pd valence electrons can intensify the electronic metal-support interactions (EMSIs) effects of Pt-Pd/CeO2 catalysts, which can weaken the Ce-O bond, thereby promoting the production and circulation of lattice oxygen and oxygen vacancies, and modulating the d-band centre to enhance the adsorption and activation of reactants. This study presents a comprehensive investigation of toluene oxidation on alloy-supported catalysts, providing practical guidance for designing reliable catalysts suitable for industrial applications.

Shifting CO2 hydrogenation from producing CO to CH3OH by engineering defect structures of Cu/ZrO2 and Cu/ZnO catalysts

The catalytic performance of supported Cu catalysts in CO2 hydrogenation is structurally dependent; hence, regulating the metal-support interactions, often driven by the redox feature of the metal oxide supports, can potentially improve catalytic performance. In this work, we demonstrate an enhanced strong metal-support interaction (SMSI) and electronic metal-support interaction (EMSI) in Cu/ZrO2 and Cu/ZnO after introducing oxygen vacancies into the catalyst supports, evidenced by more Cu encapsulation by oxide overlayers and electron transfer from the defective supports to Cu after introducing the oxygen vacancies. As a result, the defective Cu/ZrO2 and Cu/ZnO catalysts showed markedly improved MeOH production rather than CO production in the CO2 hydrogenation reaction. The in situ FTIR studies showed that the CO2 molecules preferentially adsorbed and activated into bicarbonate rather than carbonate, followed by a rapid conversion into formate on the defective catalyst. These findings highlight the special effects of defective supports in CO2 activation and conversion and catalyst design and synthesis.

Systematic Characterization of Electronic Metal-Support Interactions in Ceria-Supported Pt Particles.

Electronic metal-support interactions affect the chemical and catalytic properties of metal particles supported on reducible metal oxides, but their characterization is challenging due to the complexity of the electronic structure of these systems. These interactions often involve different states with varying numbers and positions of strongly correlated d or f electrons and the corresponding polarons. In this work, we present an approach to characterize electronic metal-support interactions by means of computationally efficient density functional calculations within the projector augmented wave method. We describe Ce3+ cations with potentials that include a Ce4f electron in the frozen core, overcoming prevalent convergence and 4f electron localization issues. We systematically explore the stability and chemical properties of different electronic states for a Pt8/CeO2(111) model system, revealing the predominant effect of electronic metal-support interactions on Pt atoms located directly at the metal-oxide interface. Adsorption energies and the reactivity of these interface Pt atoms vary significantly upon donation of electrons to the oxide support, pointing to a strategy to selectively activate interfacial sites of metal particles supported on reducible metal oxides.

Ultrafast electron transfer from CdS quantum dots to atomically-dispersed Pt for enhanced H2 evolution and value-added chemical synthesis

Photocatalytic hydrogen production is enchanting in solar energy utilization. And mechanism elucidation in interfacial electron transfer rate is a prerequisite for performance improvement. Herein, atomically dispersed Pt-modified CdS quantum dots (Pt-CdS QDs), prepared by a facile one-step in-situ deposited method, are used as a prototype. Benefiting from the maximized utilization of Pt cocatalyst as well as the strong electronic metal-support interaction, ultrafast electron transfer from CdS to Pt (∼1.7 ps) is achieved, as revealed by femtosecond transient absorption spectra. The optimal sample simultaneously realizes photocatalytic hydrogen evolution coupled with selective oxidation of 2-thiophene methanol (TM) into 2-thiophenecarboxaldehyde (TD). Specifically, it exhibits an enhanced H2-evolution rate, which is 70-fold higher than pristine CdS QDs. Moreover, a TM conversion rate of 95.3 % with a TD selectivity of 87.2 % is reached after 4 h. This work will provide some guidance for the design of photocatalytic systems with efficient interfacial electron transfer.

Boron-doping-induced modulation of structural parameters of pristine commercial carbon black for promoting Ru-catalyzed O[sbnd]H bond activation toward hydrogen evolution

Owing to the lack of adequate nucleation sites for metal nanoparticles (NPs) and weak metal-support interaction, pristine carbon materials supported metal NPs suffer from limited surface-exposed active sites and thereby low catalytic activity. Herein, we report a sodium borohydride-mediated modification of commercial Valcan carbon (VC) to produce B-doped VC (BVC) as a useful support to deposit Ru NPs (Ru/BVC) for hydrogen production from ammonia borane hydrolysis (ABH). The B-doping endows BVC with not only more surface functional groups and defect sites but also abundant meso/macroporous structure and hydrophilic surface, facilitating the generation of uniformly dispersed ultra-small Ru NPs (d = 1.42 nm) with strong electronic metal-support interaction. The optimal Ru/BVC catalyst exhibits an excellent activity with a turnover frequency of 1577.0 min−1 (depending on Ru dispersion). Isotopic and alkali promotion experiments unveil the rate-determining step (RDS) for ABH is the oxidative cleavage of the OH bond in water. The copious surface-exposed active sites and the regulated electron distribution between Ru NPs and BVC efficiently reduce the energy barrier for RDS, thereby promoting catalytic performance of hydrogen evolution from ABH. This simple and efficient heteroatom-doping strategy is easily extended to fabricate efficient catalysts with promoted performance for catalytic applications.

Ni-CeO2 nanocomposite with enhanced metal-support interaction for effective ammonia decomposition to hydrogen

Ammonia is a promising hydrogen storage material due to its ease of storage and decomposition to COx-free hydrogen. Herein, we report colloidal solution combustion synthesis (CSCS) to construct Ni-CeO2 nanocomposite catalysts for efficient ammonia decomposition to generate hydrogen. Unlike conventional supported Ni/CeO2 catalyst, the prepared Ni-CeO2 nanocomposite catalyst exhibited nickel embedded in CeO2 matrix with enhanced metal-support interaction. The physicochemical properties and metal-support interaction of the catalysts can be tuned by adjusting the amount of silica sol template. The resulted Ni-CeO2 nanocomposite catalysts exhibited outstanding catalytic performance in terms of activity and stability. The hydrogen production rate reached 32.9 mmol gcat−1 min−1 at 500 °C, which is superior to other state-of-the-art Ni-based catalysts and even comparable or better than some reported Ru-based catalysts. The systematic characterizations demonstrated that the unique Ni-CeO2 nanocomposite structure with enhanced metal-support interaction, not only provided a rich Ni-CeO2 interface to stabilize small-sized Ni nanoparticles, but also had a high concentration of oxygen vacancy to strengthen electronic metal-support interaction, making nickel surface electron-rich. The integrated studies of kinetics, temperature-programmed surface reaction, and DFT calculations corroborated that this enhanced metal-support interaction including geometric and electronic effects, favored the enrichment of NH3 on the catalyst surface and facilitated rate-determining N≡N bond formation step, thereby boosting the reaction rate. This study highlights the importance of designing new structural catalysts with enhanced metal-support interaction for boosting hydrogen production from ammonia decomposition.

Enhancing the Photocatalytic Activity of Zirconium-Based Metal-Organic Frameworks Through the Formation of Mixed-Valence Centers.

Despite the desirability of metal-organic frameworks (MOFs) as heterogeneous photocatalysts, current strategies available to enhance the performance of MOF photocatalysts are complicated and expensive. Herein, a simple strategy is presented for improving the activity of MOF photocatalysts by regulating the atomic interface structure of the metal active sites on the MOF. In this study, MOF (PCN-222) is hybridized with cellulose acetate (CA@PCN-222) through an optimized atomic interface strategy, which lowers the average valence state of Zr ions. The electronic metal-support interaction mechanism of CA@PCN-222 is revealed by evaluating the photocatalytic CO2 reduction reaction (CO2 RR). The experimental results suggested that the electron migration efficiency at the atomic interface of the MOFs strongly coupled with cellulose is significantly improved. In particular, the CO2 RR to formate activity of CA@PCN-222 photocatalyst greatly increased from 778.2 to 2816.0µmolg-1 compared with pristine PCN-222 without cellulose acetate. The findings suggest that the strongly coupled metal-ligand moiety at the atomic interface of MOFs may play a synergistic role in heterogeneous catalysts.

Tuning the properties of oxygen vacancy around Cu-Mn mixed oxides on dealumination Y zeolite by P-doping to achieve ultra-efficient catalytic ozonation of toluene with low ozone consumption

As a promising technology, ozone catalytic oxidation can effectively eliminate VOCs at low temperature. However, the excessive ozone consumption brings serious economic problems for industrial applications. Herein, Cu-Mn mixed oxides were supported on the dealumination Y zeolite, and the electronic metal-support interaction between the support and metal nanoparticles was enhanced through P-doping. Satisfyingly, the optimized catalyst P2-CuMn/DY achieved over 90% conversion of toluene even at a very harsh catalytic condition (30 °C, GHSV=240,000 h−1). Moreover, this high toluene conversion accompanying with lower ozone consumption. Compared to CuMn/DY, the ozone/toluene consumption ratio in P2-CuMn/DY decreased from ∼ 10:1 to ∼ 8.7:1. With the help of multiple various characterizations and DFT calculations, it can be found that the existence of pyrophosphate led more charge to accumulate on the surrounding metal oxides, improving the activity of oxygen vacancies. The change in the properties of oxygen vacancies enhanced the accumulation of O* species on the catalyst, improving the utilization of ozone in the catalytic reaction. This work provides a more economical strategy and guidance to design highly effective catalysts for industrial-scale VOCs eliminations.

Regulating electronic metal-support interaction by synthetic methods to enhance the toluene degradation over Pt/Co3O4 catalysts

The synthesis method of precious metal catalysts would affect the electronic metal-support interaction (EMSI) of catalysts, which further affected the catalytic activity. In this paper, Co3O4 was obtained as support by the pyrolysis of ZIF-67 as a template sacrificial agent, and Pt species were loaded by three different reduction methods. Among them, the catalyst produced by the NaBH4 reduction method possessed the best activity with T90 of 168 °C. Through a series of characterization and experiments, it was found that the EMSI of the catalyst was optimized by this synthesis method, which led to electron transfer among Pt species and Co3O4. The catalysts also exhibited excellent water resistance, stability, and recycling performance. The possible degradation mechanism of toluene was also revealed by in situ DRIFTS and GC–MS. This paper provided ideas for the construction of catalysts and a theoretical reference for the relevant verification of EMSI.

Cerium-modified Pt/Al2O3 for NH3 synthesis by NO reduction with H2

The Haber–Bosch process is a mature and proven technology for the commercial production of NH3. However, with the increasing focus on achieving net-zero emissions, alternative technologies have gained interest. This paper proposes an effective catalytic system for synthesizing NH3 directly from NO and H2 at atmospheric pressures. Pt/CeOxAl2O3 synthesized via solvent-deficient precipitation (SDP) showed a much higher NH3 yield compared to conventional Pt/Al2O3 and other Pt/Ce-containing catalysts. Various characterization techniques demonstrated that achieving precise control of the electronic metal-support interaction (EMSI) is crucial for attaining the optimal electronic and geometric structure that balances the decisive factors, Pt oxidation state and Pt dispersion, to enable a high rate of NH3 production from NO and H2. Pt/CeOxAl2O3 possesses abundant metallic Pt nanoclusters that are well dispersed on CeOxAl2O3 due to the moderate Pt-Ce interactions. These small metallic Pt clusters in contact with CeOx turned out to play a critical role in the dissociative adsorption of NO and H2, leading to the formation of the reaction intermediates, the –NH2 species, which contribute to the improved NH3 productivity of Pt/CeOxAl2O3.

Modulating Electronic Metal-Support Interactions to Boost Visible-Light-Driven Hydrolysis of Ammonia Borane: Nickel-Platinum Nanoparticles Supported on Phosphorus-Doped Titania.

Ammonia borane (AB) is a promising material for chemical H2 storage owing to its high H2 density (up to 19.6 wt %). However, the development of an efficient catalyst for driving H2 evolution through AB hydrolysis remains challenging. Therefore, a visible-light-driven strategy for generating H2 through AB hydrolysis was implemented in this study using Ni-Pt nanoparticles supported on phosphorus-doped TiO2 (Ni-Pt/P-TiO2 ) as photocatalysts. Through surface engineering, P-TiO2 was prepared by phytic-acid-assisted phosphorization and then employed as an ideal support for immobilizing Ni-Pt nanoparticles via a facile co-reduction strategy. Under visible-light irradiation at 283 K, Ni40 Pt60 /P-TiO2 exhibited improved recyclability and a high turnover frequency of 967.8 mol molPt -1 min-1 . Characterization experiments and density functional theory calculations indicated that the enhanced performance of Ni40 Pt60 /P-TiO2 originated from a combination of the Ni-Pt alloying effect, the Mott-Schottky junction at the metal-semiconductor interface, and strong metal-support interactions. These findings not only underscore the benefits of utilizing multipronged effects to construct highly active AB-hydrolyzing catalysts, but also pave a path toward designing high-performance catalysts by surface engineering to modulate the electronic metal-support interactions for other visible-light-induced reactions.