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This work investigates the one-pot conversion of furfural to 1,5-pentanediol using Cu-Co bimetallic oxide catalysts. The Cu4.5Co3.5Ox catalyst was prepared via co-precipitation, achieving a 1,5-pentanediol yield of 27.2%. Characterization techniques revealed that the activity of the catalyst is due to the synergistic interaction between Cu and Co, the electronic transfer between Cu and Co, along with a high density of medium-strength and strong acid sites. This work provides a basic data reference for rational catalyst design in the selective hydrogenation of biomass compounds, contributing to sustainable and green chemistry.

An atomic- and molecular-level understanding of heterogeneous catalysis is required to characterize the nature of active sites and improve the rational design of catalysts. Achieving this level of characterization requires techniques that can correlate catalytic performances to specific surface structures, so as to avoid averaging effects. Tip-enhanced Raman spectroscopy combines scanning probe microscopy with plasmon-enhanced Raman scattering and provides simultaneous topographical and chemical information at the nano/atomic scale from ambient to ultrahigh-vacuum and electrochemical environments. Therefore, it has been used to monitor catalytic reactions and is proposed to correlate the local structure and function of heterogeneous catalysts. Bimetallic catalysts, such as Pd-Au, show superior performance in various catalytic reactions, but it has remained challenging to correlate structure and reactivity because of their structural complexity. Here, we show that TERS can chemically and spatially probe the site-specific chemical (electronic and catalytic) and physical (plasmonic) properties of an atomically well-defined Pd(sub-monolayer)/Au(111) bimetallic model catalyst at 3nm resolution in real space using phenyl isocyanide as a probe molecule (Fig. 1a). We observe a weakened NC bond and enhanced reactivity of phenyl isocyanide adsorbed at the Pd step edge compared with that at the Pd terrace. Density functional theory corroborates these observations by revealing a higher d-band electronic profile for the low-coordinated Pd step edge atoms. The 3nm spatial resolution we demonstrate here is the result of an enhanced electric field and distinct electronic properties at the step edges.

HighlightsRecent progress in noble metal-decorated (NM-D) semiconducting metal oxides (SMOs) gas sensors are summarized.Gas sensing mechanisms related to noble metal decoration are carefully discussed.Crucial challenges facing the development of NM-D SMOs gas sensors are analyzed.Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring, exhaled breath diagnosis, and food freshness analysis. Among various chemiresistive sensing materials, noble metal-decorated semiconducting metal oxides (SMOs) have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals. This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures (e.g., nanoparticles, nanowires, nanorods, nanosheets, nanoflowers, and microspheres) for high-performance gas sensors with higher response, faster response/recovery speed, lower operating temperature, and ultra-low detection limits. The key topics include Pt, Pd, Au, other noble metals (e.g., Ag, Ru, and Rh.), and bimetals-decorated SMOs containing ZnO, SnO2, WO3, other SMOs (e.g., In2O3, Fe2O3, and CuO), and heterostructured SMOs. In addition to conventional devices, the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed. Moreover, the relevant mechanisms for the sensing performance improvement caused by noble metal decoration, including the electronic sensitization effect and the chemical sensitization effect, have also been summarized in detail. Finally, major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.

Dynamic reconstruction of metal sulphides during electrocatalytic oxygen evolution reaction (OER) has hampered the acquisition of legible evidence for comprehensively understanding the phase-transition mechanism and electrocatalytic activity origin. Herein, modelling on a series of cobalt-nickel bimetallic sulphides, we for the first time establish an explicit and comprehensive picture of their dynamic phase evaluation pathway at the pre-catalytic stage before OER process. By utilizing the in-situ electrochemical transmission electron microscopy and electron energy loss spectroscopy, the lattice sulphur atoms of (NiCo)S 1.33 particles are revealed to be partially substituted by oxygen from electrolyte to form a lattice oxygen-sulphur coexisting shell surface before the generation of reconstituted active species. Such S-O exchange process is benefitted from the subtle modulation of metal-sulphur coordination form caused by the specific Ni and Co occupation. This unique oxygen-substitution behaviour produces an (NiCo)O x S 1.33-x surface to reduce the energy barrier of surface reconstruction for converting sulphides into active oxy/hydroxide derivative, therefore significantly increasing the proportion of lattice oxygen-mediated mechanism compared to the pure sulphide surface. We anticipate this direct observation can provide an explicit picture of catalysts’ structural and compositional evolution during the electrocatalytic process. Dynamic reconstruction of metal sulphides during electrocatalytic oxygen evolution reaction is a key aspect of study. Herein, modelling on a series of cobalt-nickel bimetallic sulphides, the authors reveal a dynamic phase evaluation pathway and the S-O substitution process occurring on the catalytic surface at the pre-catalytic stage.

Nonradical Fenton-like catalysis offers opportunities to overcome the low efficiency and secondary pollution limitations of existing advanced oxidation decontamination technologies, but realizing this on transition metal spinel oxide catalysts remains challenging due to insufficient understanding of their catalytic mechanisms. Here, we explore the origins of catalytic selectivity of Fe–Mn spinel oxide and identify electron delocalization of the surface metal active site as the key driver of its nonradical catalysis. Through fine-tuning the crystal geometry to trigger Fe–Mn superexchange interaction at the spinel octahedra, ZnFeMnO₄ with high-degree electron delocalization of the Mn–O unit was created to enable near 100% nonradical activation of peroxymonosulfate (PMS) at unprecedented utilization efficiency. The resulting surface-bound PMS* complex can efficiently oxidize electron-rich pollutants with extraordinary degradation activity, selectivity, and good environmental robustness to favor water decontamination applications. Our work provides a molecule-level understanding of the catalytic selectivity and bimetallic interactions of Fe–Mn spinel oxides, which may guide the design of low-cost spinel oxides for more selective and efficient decontamination applications.

Understanding charge transfer dynamics and carrier separation pathway is challenging due to the lack of appropriate characterization strategies. In this work, a crystalline triazine/heptazine carbon nitride homojunction is selected as a model system to demonstrate the interfacial electron-transfer mechanism. Surface bimetallic cocatalysts are used as sensitive probes during in situ photoemission for tracing the S-scheme transfer of interfacial photogenerated electrons from triazine phase to the heptazine phase. Variation of the sample surface potential under light on/off confirms dynamic S-scheme charge transfer. Further theoretical calculations demonstrate an interesting reversal of interfacial electron-transfer path under light/dark conditions, which also supports the experimental evidence of S-scheme transport. Benefiting from the unique merit of S-scheme electron transfer, homojunction shows significantly enhanced activity for CO 2 photoreduction. Our work thus provides a strategy to probe dynamic electron transfer mechanisms and to design delicate material structures towards efficient CO 2 photoreduction. Here, the authors reveal how interfacial electron migration occurs in S-scheme crystalline carbon nitrides by applying several dynamic in situ characterization and theoretical calculations.

Copper is distinctive in electrocatalyzing reduction of CO₂ into various energy-dense forms, but it often suffers from limited product selectivity including ethanol in competition with ethylene. Here, we describe systematically designed, bimetallic electrocatalysts based on copper/gold heterojunctions with a faradaic efficiency toward ethanol of 60% at currents in excess of 500 mA cm−2. In the modified catalyst, the ratio of ethanol to ethylene is enhanced by a factor of 200 compared to copper catalysts. Analysis by ATR-IR measurements under operating conditions, and by computational simulations, suggests that reduction of CO₂ at the copper/gold heterojunction is dominated by generation of the intermediate OCCOH*. The latter is a key contributor in the overall, asymmetrical electrohydrogenation of CO₂ giving ethanol rather than ethylene.

Ammonia is regarded as an energy vector for hydrogen storage, transport and utilization, which links to usage of renewable energies. However, efficient catalysts for ammonia decomposition and their underlying mechanism yet remain obscure. Here we report that atomically-dispersed Ru atoms on MgO support on its polar (111) facets {denoted as MgO(111)} show the highest rate of ammonia decomposition, as far as we are aware, than all catalysts reported in literature due to the strong metal-support interaction and efficient surface coupling reaction. We have carefully investigated the loading effect of Ru from atomic form to cluster/nanoparticle on MgO(111). Progressive increase of surface Ru concentration, correlated with increase in specific activity per metal site, clearly indicates synergistic metal sites in close proximity, akin to those bimetallic N 2 complexes in solution are required for the stepwise dehydrogenation of ammonia to N 2 /H 2 , as also supported by DFT modelling. Whereas, beyond surface doping, the specific activity drops substantially upon the formation of Ru cluster/nanoparticle, which challenges the classical view of allegorically higher activity of coordinated Ru atoms in cluster form (B 5 sites) than isolated sites. Ruthenium-based materials show promising performance for ammonia decomposition, yet the underlying mechanism remains to be further explored. Here the authors investigate atomically dispersed Ru atoms on polar (111) on MgO facets to show synergistic metal sites in close proximity are required for the stepwise dehydrogenation of ammonia to N2/H2.

Single-atom catalysts (SACs) are a promising area in environmental catalysis. We report on a bimetallic Co–Mo SAC that shows excellent performance in activating peroxymonosulfate (PMS) for sustainable degradation of organic pollutants with high ionization potential (IP > 8.5 eV). Density Functional Theory (DFT) calculations and experimental tests demonstrate that the Mo sites in Mo–Co SACs play a critical role in conducting electrons from organic pollutants to Co sites, leading to a 19.4-fold increase in the degradation rate of phenol compared to the CoCl₂–PMS group. The bimetallic SACs exhibit excellent catalytic performance even under extreme conditions and show long-term activation in 10-d experiments, efficiently degrading 600 mg/L of phenol. Moreover, the catalyst has negligible toxicity toward MDA-MB-231, Hela, and MCF-7 cells, making it an environmentally friendly option for sustainable water treatment. Our findings have important implications for the design of efficient SACs for environmental remediation and other applications in biology and medicine.

The electrochemical oxygen reduction reaction (ORR) is at the heart of modern sustainable energy technologies. However, the linear scaling relationship of this multistep reaction now becomes the bottleneck for accelerating kinetics. Herein, we propose a strategy of using intermetallic-distance-regulated atomic-scale bimetal assembly (ABA) that can catalyse direct O‒O radical breakage without the formation of redundant *OOH intermediates, which could regulate the inherent linear scaling relationship and cause the ORR on ABA to follow a fast-kinetic dual-sites mechanism. Using in situ synchrotron spectroscopy, we directly observe that a self-adjustable N-bridged Pt = N 2  = Fe assembly promotes the generation of a key intermediate state (Pt‒O‒O‒Fe) during the ORR process, resulting in high reaction kinetics and selectivity. The well-designed Pt = N 2  = Fe ABA catalyst achieves a nearly two orders of magnitude enhanced kinetic current density at the half-wave potential of 0.95 V relative to commercial Pt/C and an almost 99% efficiency of 4-electron pathway selectivity, making it one of the potential ORR catalysts for application to the energy device of zinc‒air cells. This study provides a helpful design principle for developing and optimizing other efficient ORR electrocatalysts. Improving kinetics for electrochemical oxygen reduction reaction is relevant to important sustainable energy technologies. The authors propose an atomic-scale bimetal assembly consisting Pt and Fe dual sites to regulate the inherent scaling relationship between intermediates for fast kinetics.