Data‐Driven Interpretable Descriptors for the Structure–Activity Relationship of Surface Lattice Oxygen on Doped Vanadium Oxides

Interpretable Data-Driven Descriptors for Establishing the Structure-Activity Relationship of Metal-Organic Frameworks Toward Oxygen Evolution Reaction

The development of readily accessible and interpretable descriptors is pivotal yet challenging in the rational design of metal-organic framework (MOF) catalysts. This study presents a straightforward and physically interpretable activity descriptor for the oxygen evolution reaction (OER), derived from a dataset of bimetallic Ni-based MOFs. Through an artificial-intelligence (AI) data-mining subgroup discovery (SGD) approach, a combination of the d-band center and number of missing electrons in eg states of Ni, as well as the first ionization energy and number of electrons in eg states of the substituents, is revealed as a gene of a superior OER catalyst. The found descriptor, obtained from the AI analysis of a dataset of MOFs containing 3-5d transition metals and 13 organic linkers, has been demonstrated to facilitate in-depth understanding of structure-activity relationship at the molecular orbital level. The descriptor is validated experimentally for 11 Ni-based MOFs. Combining SGD with physical insights and experimental verification, our work offers a highly efficient approach for screening MOF-based OER catalysts, simultaneously providing comprehensive understanding of the catalytic mechanism.

Essential features of weak current for excellent enhancement of NOx reduction over monoatomic V-based catalyst

Human society is facing increasingly serious problems of environmental pollution and energy shortage, and up to now, achieving high NH3-SCR activity at ultra-low temperatures (<150 °C) remains challenging for the V-based catalysts with V content below 2%. In this study, the monoatomic V-based catalyst under the weak current-assisted strategy can completely convert NOx into N2 at ultra-low temperature with V content of 1.36%, which shows the preeminent turnover frequencies (TOF145 °C = 1.97×10-3 s-1). The improvement of catalytic performance is mainly attributed to the enhancement catalysis of weak current (ECWC) rather than electric field, which significantly reduce the energy consumption of the catalytic system by more than 90%. The further mechanism research for the ECWC based on a series of weak current-assisted characterization means and DFT calculations confirms that migrated electrons mainly concentrate around the V single atoms and increase the proportion of antibonding orbitals, which make the V-O chemical bond weaker (electron scissors effect) and thus accelerate oxygen circulation. The novel current-assisted catalysis in the present work can potentially apply to other environmental and energy fields.

Design Principle of Molybdenum-Based Metal Nitrides for Lattice Nitrogen-Mediated Ammonia Production

Chemical looping ammonia synthesis (CLAS) is a promising technology for reducing the high energy consumption of the conventional ammonia synthesis process. However, the comprehensive understanding of reaction mechanisms and rational design of novel nitrogen carriers has not been achieved due to the high complexity of catalyst structures and the unrevealed relationship between electronic structure and intrinsic activity. Herein, we propose a multistage strategy to establish the connection between catalyst intrinsic activity and microscopic electronic structure fingerprints using density functional theory computational energetics as bridges and apply it to the rational design of metal nitride catalysts for lattice nitrogen-mediated ammonia production. Molybdenum-based nitride catalysts with well-defined structures are employed as prototypes to elucidate the decoupled effects of electronic and geometrical features. The electron-transfer and spin polarization characteristics of the magnetic metals are constructed as descriptors to disclose the atomic-scale causes of intrinsic activity. Based on this design strategy, it is demonstrated that Ni3Mo3N catalysts possess the highest lattice nitrogen-mediated ammonia synthesis activity. This work reveals the structure-activity relationship of metal nitrides for CLAS and provides a multistage perspective on catalyst rational design.

Engineering Spin Polarization of the Surface-Adsorbed Fe Atom by Intercalating a Transition Metal Atom into the MoS2 Bilayer for Enhanced Nitrogen Reduction

The precise control of spin states in transition metal (TM)-based single-atom catalysts (SACs) is crucial for advancing the functionality of electrocatalysts, yet it presents significant scientific challenges. Using density functional theory (DFT) calculations, we propose a novel mechanism to precisely modulate the spin state of the surface-adsorbed Fe atom on the MoS2 bilayer. This is achieved by strategically intercalating a TM atom into the interlayer space of the MoS2 bilayer. Our results show that these strategically intercalated TM atoms can induce a substantial interfacial charge polarization, thereby effectively controlling the charge transfer and spin polarization on the surface Fe site. In particular, by varying the identity of the intercalated TM atoms and their vacancy filling site, a continuous modulation of the spin states of the surface Fe site from low to medium to high can be achieved, which can be accurately described using descriptors composed of readily accessible intrinsic properties of materials. Using the electrochemical dinitrogen reduction reaction (eNRR) as a prototypical reaction, we discovered a universal volcano-like relation between the tuned spin and the catalytic activity of Fe-based SACs. This finding contrasts with the linear scaling relationships commonly seen in traditional studies and offers a robust new approach to modulating the activity of SACs through interfacial engineering.

Toward the Rational Design of More Efficient Mo2C Catalysts for Hydrodeoxygenation-Mechanism and Descriptor Identification

Viable alternatives to scarce and expensive noble-metal-based catalysts are transition-metal carbides such as Mo and W carbides. It has been shown that these are active and selective catalysts in the hydrodeoxygenation of renewable lipid-based feedstocks. However, the reaction mechanism and the structure-activity relationship of these transition-metal carbides have not yet been fully clarified. In this work, the reaction mechanism of butyric acid hydrodeoxygenation (HDO) over molybdenum carbide (Mo2C) has been studied comprehensively by means of density functional theory coupled with microkinetic modeling. We identified the rate-determining step to be butanol dissociation: C4H9*OH + * → C4H9* + *OH. Then we further explored the possibility to facilitate this step upon heteroatom doping and found that Zr- and Nb-doped Mo2C are the most promising catalysts with enhanced HDO catalytic activity. Linear-scaling relationships were established between the electronic and geometrical descriptors of the dopants and the catalytic performance of various doped Mo2C catalysts. It was demonstrated that descriptors such as dopants' d-band filling and atomic radius play key roles in governing the catalytic activity. This fundamental understanding delivers practical strategies for the rational design of Mo2C-based transition-metal carbide catalysts with improved HDO performance.

Direct observation of accelerating hydrogen spillover via surface-lattice-confinement effect

Uncovering how hydrogen transfers and what factors control hydrogen conductivity on solid surface is essential for enhancing catalytic performance of H-involving reactions, which is however hampered due to the structural complexity of powder catalysts, in particular, for oxide catalysts. Here, we construct stripe-like MnO(001) and grid-like Mn3O4(001) monolayers on Pt(111) substrate and investigate hydrogen spillover atop. Atomic-scale visualization demonstrates that hydrogen species from Pt diffuse unidirectionally along the stripes on MnO(001), whereas it exhibits an isotropic pathway on Mn3O4(001). Dynamic surface imaging in H2 atmosphere reveals that hydrogen diffuses 4 times more rapidly on MnO than the case on Mn3O4, which is promoted by one-dimension surface-lattice-confinement effect. Theoretical calculations indicate that a uniform and medium O-O distance favors hydrogen diffusion while low-coordinate surface O atom inhibits it. Our work illustrates the surface-lattice-confinement effect of oxide catalysts on hydrogen spillover and provides a promising route to improve the hydrogen spillover efficiency.

Periodic Arrays of Metal Nanoclusters on Ultrathin Fe-Oxide Films Modulated by Metal-Oxide Interactions

Rational design of highly stable and active metal catalysts requires a deep understanding of metal-support interactions at the atomic scale. Here, ultrathin films of FeO and FeO2-x grown on Pt(111) are used as templates for the construction of well-defined metal nanoclusters. Periodic arrays of Cu clusters in the form of monomers and trimers are preferentially located at FCC domains of FeO/Pt(111) surface, while the selective location of Cu clusters at FeO2 domains is observed on FeO2-x /Pt(111) surface. The preferential nucleation and formation of well-ordered Cu clusters are driven by different interactions of Cu with the Fe oxide domains in the sequence of FeO2-FCC > FeO-FCC > FeO-HCP > FeO-TOP, which is further validated by density functional theory calculations. It has been revealed that the p-band center as a reactivity descriptor of surface O atoms determines the interaction between metal adatoms and Fe oxides. The modulated metal-oxide interaction provides guidance for the rational design of supported single-atom and nanocluster catalysts.