Enhanced mesoporous metal-support interaction through d-d orbitals hybridization for advanced hydrogen evolution catalysis.

The impact of support surface area on the SMSI decoration effect and catalytic performance for Fischer-Tropsch synthesis of Co-Ru/TiO2-anatase catalysts

Presently, minimizing the usage and boosting the electrocatalytic efficiency of the otherwise costly platinum group-based materials appear to be the only practical option for commercial utilization of electrochemical energy conversion devices. To this end, exploring the suitability of multifunctional catalyst materials could be a promising strategy. In this regard, combining the different functionalities like hybrids of inorganic and organic materials could be a potential approach. However, a comprehensive mechanistic understanding about the role of composition to the catalytically active sites in multifunctional electrocatalysts is crucial for the design of suitably active and durable electrocatalysts for these devices. To address this, we attempted to explore and understand the combined effect of alloying and graphene oxide (GO) support interactions over the electrocatalytic activity of Pt-Co/rGO electrocatalysts. For this, Pt-Co/rGO nanoalloys with varying Pt:Co ratios were prepared via simple hydrothermal treatment and tested for three important fuel cell reactions viz. oxygen reduction, methanol oxidation, and hydrogen evolution reactions. Among the so-crafted and electrocatalytically explored Pt:Co compositions viz. 1:1, 1:3, and 3:1 (with and without GO), the GO composite with a Pt:Co molar ratio of 1:1, i.e., Pt1Co1/rGO demonstrated the best electrocatalytic activity and durability for long-term electrolysis. The significantly enhanced multifunctional catalytic activity and stability of the crafted catalysts are attributed to the synergism between Pt-Co nanoalloys and rGO support that modifies the d-band electronic structure of Pt via ‘strong metal–support interaction’ and to the lattice strain induced by nanoalloying of Pt with Co.

We present a controlled fabrication of selective ultrathin metal–organic framework (MOF) nanosheets as preassembling platforms, yolk–shell structured with a few-layered N-doped carbon (NC) shell-en...

The strong metal-support interaction (SMSI) in supported metal catalysts represents a crucial factor in the design of highly efficient heterogeneous catalysts. This interaction can modify the surface adsorption state, electronic structure, and coordination environment of the supported metal, altering the interface structure of the catalyst. These changes serve to enhance the catalyst's activity, stability, and reaction selectivity. In recent years, a multitude of researchers have uncovered a range of novel SMSI types and induction methods including oxidized SMSI (O-SMSI), adsorbent-mediated SMSI (A-SMSI), and wet chemically induced SMSI (Wc-SMSI). Consequently, a systematic and critical review is highly desirable to illuminate the latest advancements in SMSI and to deliberate its application within heterogeneous catalysts. This article provides a review of the characteristics of various SMSI types and the most recent induction methods. It is concluded that SMSI significantly contributes to enhancing catalyst stability, altering reaction selectivity, and increasing catalytic activity. Furthermore, this paper offers a comprehensive review of the extensive application of SMSI in the electrocatalysis of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and carbon dioxide reduction reaction (CO2RR). Finally, the opportunities and challenges that SMSI faces in the future are discussed.

Pt modified NiMoO4-GO/NF nanorods with strong metal-support interaction as efficient bifunctional catalysts for overall water splitting

The formation of metal-oxide interfaces in catalytic systems exhibits a synergistic phenomenon between metal and reducible oxides, often referred to as the strong metal–support interaction (SMSI). This unusual characteristic has been connected to the origin of highly enhanced catalytic performance for decades, but the mechanistic explanation of SMSI remains a long-standing issue in heterogeneous catalysis. To understand this matter at the molecular level, geometric and electronic functions of metal-oxide interfaces during catalytic reactions should be clearly interpreted using advanced microscopic and spectroscopic analysis techniques. In this Review, we highlight recently performed investigations at metal-oxide interfaces by operando characterization tools to identify active sites in working conditions. We introduce two kinds of catalysts, platinum-based bimetallic alloys and mixed metal-oxide catalysts. Selected operando techniques reveal their atomic-scale morphology, surface electronic structure, and charge transfer/transport at surfaces under oxidation, reduction, and gas mixture environments. With bimetallic model catalysts, topographic morphology observations present critical evidence for the structural modulation between the topmost layer and the subsurface lattice in oxygen conditions. For the mixed metal-oxide catalysts, we note that metal nanoparticles on reducible oxides demonstrate the catalytic activity enhancement, which is obviously influenced by the change of oxidation states at the metal-oxide interface. Environmental transmission electron microscopy images unveil the atomic-scale redox behaviors at the nanoparticle interfaces with evolutions of the reducible oxide under the catalytic reaction. The important role of reactive interfaces between the transition metal atom and oxide-support explains the surface chemistry and heterogeneous catalysis over active sites on well-defined single crystal model surfaces, as well as nanoparticle catalysts. Overall, operando studies for metal-oxide interfaces can shed light on mechanistic insights into the tuning of catalytic activity at the molecular level and on improving catalytic performance by the SMSI effect.

Light-enhanced metal-support interaction for synergetic photo/thermal catalytic formaldehyde oxidation

The optimization of metal-support interactions is used to fabricate noble metal-based nanoclusters with high activity for hydrogen evolution reaction (HER) in acid media. Specifically, the oxygen-defective Mn3O4 nanosheets supported Pt nanoclusters of ≈1.71nm in diameter (Pt/V·-Mn3O4 NSs) are synthesized through the controlled solvothermal reaction. The Pt/V·-Mn3O4 NSs show a superior activity and excellent stability for the HER in the acidic media. They only require an overpotential of 19mV to drive -10mAcm-2 and show negligible activity loss at -10 and -250mAcm-2 for >200 and >60h, respectively. Their Pt mass activity is 12.4 times higher than that of the Pt/C and even higher than those of many single-atom based Pt catalysts. DFT calculations show that their high HER activity arises mainly from the strong metal-support interaction between Pt and Mn3O4. It can facilitate the charge transfer from Mn3O4 to Pt, optimizing the H adsorption on the catalyst surface and promoting the evolution of H2 through the Volmer-Tafel mechanism. The oxygen vacancies in the V·-Mn3O4 NSs are found to be inconducive to the high activity of the Pt/V·-Mn3O4 NSs, highlighting the great importance to reduce the vacancy levels in V·-Mn3O4 NSs.

Influence of the SMSI effect on the catalytic activity of a Pt(1%)/Ce0.6Zr0.4O2 catalyst: SAXS, XRD, XPS and TPR investigations

This perspective focuses on the modulation of metal-support interaction (MSI) in catalysts for COx hydrogenation, highlighting their profound impact on catalytic performance. Firstly, it outlines different strategies, including the use of highly reducible oxides and moderate reduction treatments, which induce the classical strong metal-support interaction (SMSI) effect and the electronic metal-support interaction (EMSI) effect. Morphology engineering and crystalline phase manipulation of oxides presented as effective methods to control EMSI are also discussed. The discrimination of SMSI and EMSI can be achieved using oxides with low encapsulation tendencies, such as ZrO2, which supports electronic modifications without or minimizing the overgrowth issues, optimizing the catalytic performance for methanation. Then, the synergy between Cu and ZnO in methanol synthesis, enhanced by SMSI, is emphasized inside. Optimizing support oxides to control oxygen vacancies enhances the catalytic performance of CO2 hydrogenation to methanol. Perspectives for the future research on the fundamental understanding of structure-MSI-performance relationship for catalyst design is discussed.

Chapter 8 Carrier Effect on Hydrogenation Properties of Metals

High overpotential and poor long‐term operation stability of electrocatalysts are two major barriers for the hydrogen evolution reaction (HER). Herein, 2D ultrathin PdAgAu nanorings are synthesized and further self‐assembled on Ti2CTx–graphene oxide (GO) heterostructure for efficiently boosting HER. The best candidate, Pd50Ag31Au19/Ti2CTx–GO electrocatalyst, can initiate hydrogen evolution at an overpotential of 90 mV at 10 mA cm−2 and exhibits the lowest Tafel slope of 75 mV dec−1 as well as the highest mass activity of 284.4 mA mg−1Pd at −100 mV, in comparison with those of Pd50Ag31Au19/Ti2CTx, Pd50Ag31Au19/GO, and commercial Pd/C. Most remarkably, impressive long‐term stability is achieved even after a 112 h chronoamperometric test. The great performance of Pd50Ag31Au19/Ti2CTx–GO electrocatalyst can be attributed to the advantageous synergistic effect among the morphological modulation, composition optimization, and strong metal–support interaction effect between the Pd50Ag31Au19 nanorings and Ti2CTx–GO support.

Hydrazine oxidation-assisted hydrogen evolution represents a promising avenue for energy-saving hydrogen production. However, the development of bifunctional catalysts with high atom economy and durability for both hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER) remains challenging. Here, a design is reported that combines sulfur-stabilized Pt clusters and Ni-N4 sites on nitrogen-doped carbon support (Ptn-S/Ni1-NC) for boosting alkaline hydrazine oxidation-assisted hydrogen evolution. Experimental and theoretical results reveal that the pre-coordinated sulfur atoms on Pt clusters provide strong metal-support interaction (SMSI) for the homogeneous distribution of Pt clusters, allowing Pt clusters to remain ultrafine, which ensures high atom utilization and sufficient active sites. Moreover, the electronic interactions and synergistic adsorption mechanism of Pt clusters and adjacent Ni-N4 sites markedly accelerate the H2O dissociation and HzOR kinetics. As a result, the Ptn-S/Ni1-NC catalysts exhibit exceptional catalytic activity, achieving an ultrasmall HER overpotential of 19mV and an ultralow HzOR working potential of -21mV at 10mAcm-2 current density. In addition, the overall hydrazine oxidation-assisted splitting (OHzS) electrolyzer can reach 10mAcm-2 with a low cell voltage of 79mV and good long-term stability in 1.0m KOH/0.5m N2H4.

Modulating the strong metal-support interactions by regulating the chemical microenvironment of Pt confined in MOFs for low temperature hydrogenation of DCPD

Gold nanoparticles (Au NPs) deposited on various cation- and anion-substituted hydroxyapatites (Au/sHAPs) show oxidative strong metal-support interaction (SMSI), wherein a thin layer of the sHAP covered the surface of the Au NPs by heat treatment in an oxidative atmosphere. Calcination of Au/sHAPs at 300 °C caused a partial SMSI and that at 500 °C gave fully encapsulated Au NPs. We investigated the influence of the substituted ions in sHAP and the degree of the oxidative SMSI on the catalytic performance of Au/sHAPs for oxidative esterification of octanal or 1-octanol with ethanol to obtain ethyl octanoate. The catalytic activity depends on the size of the Au NPs but not on the support used, owing to the similarity of the acid and base properties of sHAPs except for Au/CaFAP. The presence of a large number of acidic sites on CaFAP lowered the product selectivity, but all other sHAPs exhibited similar activity when the Au particle size was almost the same, owing to the similarity of the acid and base properties. Au/sHAPs_O2 with SMSI exhibited higher catalytic activity than Au/sHAPs_H2 without SMSI despite the fact that the number of exposed surface Au atoms was decreased by the SMSI. In addition, the oxidative esterification reaction proceeded even though the Au NPs were fully covered by the sHAP layer when the thickness of the layer was controlled to be less than 1 nm. The substrate can access the surfaces of the Au NPs covered by the thin sHAP layer (<1 nm), and the presence of the sHAP structure in close contact with the Au NPs resulted in significantly higher catalytic activity compared with that for fully exposed Au NPs deposited on the sHAPs. This result suggests that maximizing the contact area between the Au NPs and the sHAP support based on the SMSI enhances the catalytic activity of Au.