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Compared to H 2 -assisted activation mode, the direct dissociation of CO 2 into carbonyl (*CO) with a simplified reaction route is advantageous for CO 2 -related synthetic processes and catalyst upgrading, while the stable C = O double bond makes it very challenging. Herein, we construct a subnano MoO 3 layer on the surface of Mo 2 N, which provides a dynamically changing surface of MoO 3 ↔MoO x (x < 3) for catalyzing CO 2 hydrogenation. Rich oxygen vacancies on the subnano MoO x surface with a high electron donating capacity served as a scissor to directly shear the C = O double bond of CO 2 to form CO at a high rate. The O atoms leached in CO 2 dissociation are removed timely by H 2 to regenerate active oxygen vacancies. Owing to the greatly enhanced dissociative activation of CO 2 , this MoO x /Mo 2 N catalyst without any supported active metals shows excellent performance for catalyzing CO 2 hydrogenation to CO. The construction of highly disordered defective surface on heterostructures paves a new pathway for molecule activation., (© 2024. The Author(s).)

The reverse water gas shift reaction can be considered as a promising route to mitigate global warming by converting CO 2 into syngas in a large scale, while it is still challenging for non-Cu-based catalysts to break the trade-off between activity and selectivity. Here, the relatively high loading of Ni species is highly dispersed on hydroxylated TiO 2 through the strong Ni and -OH interactions, thereby inducing the formation of rich and stable Ni clusters (~1 nm) on anatase TiO 2 during the reverse water gas shift reaction. This Ni cluster/TiO 2 catalyst shows a simultaneous high CO 2 conversion and high CO selectivity. Comprehensive characterizations and theoretical calculations demonstrate Ni cluster/TiO 2 interfacial sites with strong CO 2 activation capacity and weak CO adsorption are responsible for its unique catalytic performances. This work disentangles the activity-selectivity trade-off of the reverse water gas shift reaction, and emphasizes the importance of metal-OH interactions on surface., (© 2024. The Author(s).)

Oxygen vacancy (O v ) is an anionic defect widely existed in metal oxide lattice, as exemplified by CeO 2 , TiO 2 , and ZnO. As O v can modify the band structure of solid, it improves the physicochemical properties such as the semiconducting performance and catalytic behaviours. We report here a new type of O v as an intrinsic part of a perfect crystalline surface. Such non-defect O v stems from the irregular hexagonal sawtooth-shaped structure in the (111) plane of trivalent rare earth oxides (RE 2 O 3 ). The materials with such intrinsic O v structure exhibit excellent performance in ammonia decomposition reaction with surface Ru active sites. Extremely high H 2 formation rate has been achieved at ~1 wt% of Ru loading over Sm 2 O 3 , Y 2 O 3 and Gd 2 O 3 surface, which is 1.5-20 times higher than reported values in the literature. The discovery of intrinsic O v suggests great potentials of applying RE oxides in heterogeneous catalysis and surface chemistry., (© 2024. The Author(s).)

Dual-interfacial structure within catalysts is capable of mitigating the detrimentally completive adsorption during the catalysis process, but its construction strategy and mechanism understanding remain vastly lacking. Here, a highly active dual-interfaces of CeO 2-x /CoO 1-x /Co is constructed using the pronounced interfacial interaction from surrounding small CeO 2-x islets, which shows high activity in catalyzing the water-gas shift reaction. Kinetic evidence and in-situ characterization results revealed that CeO 2-x modulates the oxidized state of Co species and consequently generates the dual active CeO 2-x /CoO 1-x /Co interface during the WGS reaction. A synergistic redox mechanism comprised of independent contribution from dual functional interfaces, including CeO 2-x /CoO 1-x and CoO 1-x /Co, is authenticated by experimental and theoretical results, where the CeO 2-x /CoO 1-x interface alleviates the CO poison effect, and the CoO 1-x /Co interface promotes the H 2 formation. The results may provide guidance for fabricating dual-interfacial structures within catalysts and shed light on the mechanism over multi-component catalyst systems., (© 2023. The Author(s).)

In heterogeneous catalysis, the interface between active metal and support plays a key role in catalyzing various reactions. Specially, the synergistic effect between active metals and oxygen vacancies on support can greatly promote catalytic efficiency. However, the construction of high-density metal-vacancy synergistic sites on catalyst surface is very challenging. In this work, isolated Pt atoms are first deposited onto a very thin-layer of MoO 3 surface stabilized on γ-Mo 2 N. Subsequently, the Pt-MoO x /γ-Mo 2 N catalyst, containing abundant Pt cluster-oxygen vacancy (Pt n -O v ) sites, is in situ constructed. This catalyst exhibits an unmatched activity and excellent stability in the reverse water-gas shift (RWGS) reaction at low temperature (300 °C). Systematic in situ characterizations illustrate that the MoO 3 structure on the γ-Mo 2 N surface can be easily reduced into MoO x (2 < x < 3), followed by the creation of sufficient oxygen vacancies. The Pt atoms are bonded with oxygen atoms of MoO x , and stable Pt clusters are formed. These high-density Pt n -O v active sites greatly promote the catalytic activity. This strategy of constructing metal-vacancy synergistic sites provides valuable insights for developing efficient supported catalysts., (© 2022. The Author(s).)

The metal-support interfaces between metals and oxide supports have long been studied in catalytic applications, thanks to their significance in structural stability and efficient catalytic activity. The metal-rare earth oxide interface is particularly interesting because these early transition cations have high electrophilicity, and therefore good binding strength with Lewis basic molecules, such as H 2 O. Based on this feature, here we design a highly efficient composite Ni-Y 2 O 3 catalyst, which forms abundant active Ni-NiO x -Y 2 O 3 interfaces under the water-gas shift (WGS) reaction condition, achieving 140.6 μmol CO g cat -1 s -1 rate at 300 °C, which is the highest activity for Ni-based catalysts. A combination of theory and ex/in situ experimental study suggests that Y 2 O 3 helps H 2 O dissociation at the Ni-NiO x -Y 2 O 3 interfaces, promoting this rate limiting step in the WGS reaction. Construction of such new interfacial structure for molecules activation holds great promise in many catalytic systems., (© 2022. The Author(s).)

For high-temperature catalytic reaction, it is of significant importance and challenge to construct stable active sites in catalysts. Herein, we report the construction of sufficient and stable copper clusters in the copper‒ceria catalyst with high Cu loading (15 wt.%) for the high-temperature reverse water gas shift (RWGS) reaction. Under very harsh working conditions, the ceria nanorods suffered a partial sintering, on which the 2D and 3D copper clusters were formed. This partially sintered catalyst exhibits unmatched activity and excellent durability at high temperature. The interaction between the copper and ceria ensures the copper clusters stably anchored on the surface of ceria. Abundant in situ generated and consumed surface oxygen vacancies form synergistic effect with adjacent copper clusters to promote the reaction process. This work investigates the structure-function relation of the catalyst with sintered and inhomogeneous structure and explores the potential application of the sintered catalyst in C1 chemistry., (© 2022. The Author(s).)

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO 2 production rate of 487 μmol CO2 ·g Pt -1 ·s -1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt-O-Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors 1-10 . The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO 2 (refs. 11,12 ) has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO 2 and NdNiO 2 , while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with [Formula: see text] symmetry in the NiO 2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics 13-15 , which are well known for heavy fermion behaviour, where the NiO 2 correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like 'oxide-intermetallic' replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.

As the water-gas shift (WGS) reaction serves as a crucial industrial process, strategies for developing robust WGS catalysts are highly desiderated. Here we report the construction of stabilized bulk-nano interfaces to fabricate highly efficient copper-ceria catalyst for the WGS reaction. With an in-situ structural transformation, small CeO 2 nanoparticles (2-3 nm) are stabilized on bulk Cu to form abundant CeO 2 -Cu interfaces, which maintain well-dispersed under reaction conditions. This inverse CeO 2 /Cu catalyst shows excellent WGS performances, of which the activity is 5 times higher than other reported Cu catalysts. Long-term stability is also very solid under harsh conditions. Mechanistic study illustrates that for the inverse CeO 2 /Cu catalyst, superb capability of H 2 O dissociation and CO oxidation facilitates WGS process via the combination of associative and redox mechanisms. This work paves a way to fabricate robust catalysts by combining the advantages of bulk and nano-sized catalysts. Catalysts with such inverse configurations show great potential in practical WGS applications.

Small-size (<5 nm) gold nanostructures supported on reducible metal oxides have been widely investigated because of the unique catalytic properties they exhibit in diverse redox reactions. However, arguments about the nature of the gold active site have continued for two decades, due to the lack of comparable catalyst systems with specific gold species, as well as the scarcity of direct experimental evidence for the reaction mechanism under realistic working conditions. Here we report the determination of the contribution of single atoms, clusters and particles to the oxidation of carbon monoxide at room temperature, by the aid of in situ X-ray absorption fine structure analysis and in situ diffuse reflectance infrared Fourier transform spectroscopy. We find that the metallic gold component in clusters or particles plays a much more critical role as the active site than the cationic single-atom gold species for the room-temperature carbon monoxide oxidation reaction.

How coherent quasiparticles emerge by doping quantum antiferromagnets is a key question in correlated electron systems, whose resolution is needed to elucidate the phase diagram of copper oxides. Recent resonant inelastic X-ray scattering (RIXS) experiments in hole-doped cuprates have purported to measure high-energy collective spin excitations that persist well into the overdoped regime and bear a striking resemblance to those found in the parent compound, challenging the perception that spin excitations should weaken with doping and have a diminishing effect on superconductivity. Here we show that RIXS at the Cu L3-edge indeed provides access to the spin dynamical structure factor once one considers the full influence of light polarization. Further we demonstrate that high-energy spin excitations do not correlate with the doping dependence of Tc, while low-energy excitations depend sensitively on doping and show ferromagnetic correlations. This suggests that high-energy spin excitations are marginal to pairing in cuprate superconductors.