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We have studied the decomposition of methanol-d4 on thin film Al2O3/NiAl(100) under near-ambient-pressure conditions, with varied surface-probe techniques and calculations based on density-functional theory. Methanol-d4 neither adsorbed nor reacted on Al2O3/NiAl(100) at 400 K under ultrahigh vacuum conditions, whereas they dehydrogenated, largely to methoxy-d3 (CD3O*, * denoting adsorbates) and formaldehyde-d2 (CD2O*), on the surface when the methanol-d4 partial pressure was increased to 10−3 mbar and above. The dehydrogenation was facilitated by hydroxyl (OH* or OD*) from the dissociation of little co-adsorbed water; a small fraction of CD2O* interacted further with OH* (OD*) to form, via intermediate CD2OOH* (CD2OOD*), formic acid (DCOOH* or DCOOD*). A few surface carbonates were also yielded, likely on the defect sites of Al2O3/NiAl(100). The results suggest that alumina not only supports metal clusters but also participates in reactions under realistic catalytic conditions. One may consider accordingly the multiple functions of alumina while designing ideal catalysts. [ABSTRACT FROM AUTHOR]

Shifting from the typical 4e– pathway to H2O in electrochemical oxygen reduction to the 2e– pathway to H2O2 is increasingly recognized as an environmentally friendly approach for producing H2O2. However, the competitive 4e− pathway is a significant obstacle to the production of H2O2 since H2O is the thermodynamically favored product. Here, a series of Pt, Pd, and Rh active atoms diluted within inert‐Au matrices with precisely controlled atomic arrangements and coordination environments are synthesized via facet engineering for O2‐to‐H2O2 production. Surprisingly, individually dispersed Pt atoms within the Au surface enclosed by the square atomic arrangements exhibit superior H2O2 selectivity and achieve a maximum selectivity of 90% at 0.36 V versus the reversible hydrogen electrode. Operando synchrotron ambient pressure X‐ray photoelectron spectroscopy identifies the presence of *OOH key intermediates on these isolated Pt active sites. Grand canonical density‐functional theory also reveals that the kinetic energy barrier for the 2e− pathway (0.08 eV; OOH* + H+ + e− → H2O2) on the isolated Pt sites is significantly lower than the 4e− pathway (0.29 eV; OOH* + H+ + e− → O* + H2O). This work enables atomic‐scale control in dilute binary alloy surfaces with specific configurations of isolated active atoms and provides essential guidance for catalyst design to boost O2‐to‐H2O2 production. [ABSTRACT FROM AUTHOR]

The decomposition of methanol-d4 (CD3OD) on Rh nanoclusters grown by the deposition of Rh vapors onto an ordered thin film of Al2O3/NiAl(100) was studied, with various surface-probe techniques and largely under near-ambient-pressure (NAP) conditions. The results showed a superior reactivity of small Rh clusters (diameter < 1.5 nm) exposed to CD3OD at 5 × 10−3–0.1 mbar at 400 K; the gaseous production of CO and D2 from decomposed methanol-d4 per Rh surface site on the small Rh clusters with diameters of ∼1.1 nm was nearly 8 times that on large ones with diameters of ∼3.5 nm. The promotion of reactivity with decreased cluster size under NAP conditions was evidently greater than that under ultrahigh vacuum conditions. Moreover, the concentration of atomic carbon (C*; where * denotes adsorbate)—a key catalyst poisoner—yielded from the dissociation of CO* from dehydrogenated methanol-d4 was significantly smaller on small clusters (diameter < 1.5 nm). The NAP size effect on methanol-d4 decomposition involved the surface hydroxyl (OH*) from the little co-adsorbed water (H2O*) that was dissociated at a probability dependent on the cluster size. H2O* was more likely dissociated into OH* on small Rh clusters, by virtue of their more reactive d-band structure, and the OH* then effectively promoted the O–D cleavage of methanol-d4, as the rate-determining step, and thus the reaction probability; on the other hand, the OH* limited CO* dissociation on small Rh clusters via both adsorbate and lateral effects. These results suggest that the superior properties of small Rh clusters in both reactivity and anti-poisoning would persist and be highly applicable under "real-world" catalysis conditions. [ABSTRACT FROM AUTHOR]

Using lightweight and inexpensive aluminum foil as a current collector in aqueous batteries is still very challenging due to its serious corrosion effects, which impede the practical applications of aqueous batteries. In this study, Pc is proposed as a corrosion inhibitor for aluminum current collectors. Interestingly, the corrosion current density (0.013 μA) in an aqueous electrolyte with the Pc additive is 23 times less than that (0.302 μA) without Pc. Furthermore, a Zn/LVPF cell was used to assess the corrosion impact on its battery performance in an aqueous electrolyte. Zn‖LVPF cells at a 0.2C rate with the Pc additive demonstrated a higher capacity retention of 75% and 50.12% after 100 and 200 cycles, respectively. The battery without Pc showed a substantially worse cycle life with only 27.57% capacity retention after 40 cycles. Furthermore, Pc prevents aluminum corrosion in an organic electrolyte-based battery. The Pc additive can protect aluminum from corrosion by a dual-secure passivation mechanism, including its physical adsorption on the Al surfaces and electrochemically formed AlPc-F passivation layer. This work opens a new avenue for developing corrosion inhibitors of aluminum not only in aqueous electrolytes but also for organic-based electrolytes. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides, by virtue of their two-dimensional structures, could provide the largest active surface for reactions with minimal materials consumed, which has long been pursued in the design of ideal catalysts. Nevertheless, their structurally perfect basal planes are typically inert; their surface defects, such as under-coordinated atoms at the surfaces or edges, can instead serve as catalytically active centers. Here we show a reaction probability > 90 % for adsorbed methanol (CH3OH) on under-coordinated Pt sites at surface Te vacancies, produced with Ar+ bombardment, on layered PtTe2 — approximately 60 % of the methanol decompose to surface intermediates CHxO (x = 2, 3) and 35 % to CHx (x = 1, 2), and an ultimate production of gaseous molecular hydrogen, methane, water and formaldehyde. The characteristic reactivity is attributed to both the triangular positioning and varied degrees of oxidation of the under-coordinated Pt at Te vacancies.Methanol on under-coordinated Pt sites at surface Te vacancies on layered PtTe2 decomposes at a probability >90 % which ultimately produces gaseous molecular hydrogen, methane, water and formaldehyde. [ABSTRACT FROM AUTHOR]

FeCx catalysts (Fe-CN-Py) were synthesized by co-pyrolyzing the mixture of iron nitrate and a CN source (melamine, bulk g-C3N4 (b-C3N4), or defective g-C3N4 (d-C3N4)). The physicochemical properties of Fe-CN-Py catalysts and their activities of CO2 hydrogenation to light hydrocarbon (C2-C6) were analyzed. The results indicated that Fe-d-C3N4-(0.3)-Py is the most promising with the highest CO2 conversion (47.2%), olefin yield (10.8%), and olefin space-time yield (STY = 4.5 µmol olefin/s/gFe). The promising activity of Fe-d-C3N4-(0.3)-Py was attributed to its high concentration of surface FeCx. The correlation between surface FeCx and the STY of hydrocarbons and olefins was established. [ABSTRACT FROM AUTHOR]