Fast Surface Oxygen Release Kinetics Accelerate Nanoparticle Exsolution in Perovskite Oxides.

Exsolution is a recent advancement for fabricating oxide-supported metal nanoparticle catalysts via phase precipitation out of a host oxide. A fundamental understanding and control of the exsolution kinetics are needed to engineer exsolved nanoparticles to obtain higher catalytic activity toward clean energy and fuel conversion. Since oxygen release via oxygen vacancy formation in the host oxide is behind oxide reduction and metal exsolution, we hypothesize that the kinetics of metal exsolution should depend on the kinetics of oxygen release, in addition to the kinetics of metal cation diffusion. Here, we probe the surface exsolution kinetics both experimentally and theoretically using thin-film perovskite SrTi0.65Fe0.35O3 (STF) as a model system. We quantitatively demonstrated that in this system the surface oxygen release governs the metal nanoparticle exsolution kinetics. As a result, by increasing the oxygen release rate in STF, either by reducing the sample thickness or by increasing the surface reactivity, one can effectively accelerate the Fe0 exsolution kinetics. Fast oxygen release kinetics in STF not only shortened the prereduction time prior to the exsolution onset, but also increased the total quantity of exsolved Fe0 over time, which agrees well with the predictions from our analytical kinetic modeling. The consistency between the results obtained from in situ experiments and analytical modeling provides a predictive capability for tailoring exsolution, and highlights the importance of engineering host oxide surface oxygen release kinetics in designing exsolved nanocatalysts.

Structure Matters: Asymmetric CO Oxidation at Rh Steps with Different Atomic Packing.

Curved crystals are a simple but powerful approach to bridge the gap between single crystal surfaces and nanoparticle catalysts, by allowing a rational assessment of the role of active step sites in gas-surface reactions. Using a curved Rh(111) crystal, here, we investigate the effect of A-type (square geometry) and B-type (triangular geometry) atomic packing of steps on the catalytic CO oxidation on Rh at millibar pressures. Imaging the crystal during reaction ignition with laser-induced CO2 fluorescence demonstrates a two-step process, where B-steps ignite at lower temperature than A-steps. Such fundamental dissimilarity is explained in ambient pressure X-ray photoemission (AP-XPS) experiments, which reveal partial CO desorption and oxygen buildup only at B-steps. AP-XPS also proves that A-B step asymmetries extend to the active stage: at A-steps, low-active O-Rh-O trilayers buildup immediately after ignition, while highly active chemisorbed O is the dominant species on B-type steps. We conclude that B-steps are more efficient than A-steps for the CO oxidation.

One-year real-world outcomes of bevacizumab for the treatment of macular oedema secondary to retinal vein occlusion.

BACKGROUND: Bevacizumab is the only agent that many people can afford, yet there are only limited data on whether it improves macular oedema (MO) secondary to retinal vein occlusion (RVO) in real-world clinical practice. Here we studied 12-month real-world treatment outcomes of bevacizumab for RVO-related MO. METHODS: This was a multicentre, observational study analysing 12-month data from the Fight Retinal Blindness! (FRB) database. We studied treatment-naïve eyes with MO secondary to RVO commencing bevacizumab therapy between June 2009 and June 2019. Visual acuity (VA) and central subfield thickness (CST) were measured at baseline, 6 and 12 months. The primary outcome was a change in VA from baseline to 12 months. RESULTS: Two hundred and twenty treatment naive eyes were analyzed. The baseline VA for BRVO was better than CRVO (55.8 vs. 42.6 LogMAR letters) and this gap widened over the 12-month period, with a 12-month VA change of +14.0 (95% CI 11.1, 16.8) letters for BRVO and + 11.9 (95% CI 6.4, 17.4) for CRVO. The mean CST at baseline was 511 µm for BRVO and 627 µm for CRVO, falling at 12 months by -155 µm (-190, -121) in BRVO and -198 µm (-252, -145) in CRVO. The median number of injections for BRVO and CRVO completers was 7 (5, 9). CONCLUSIONS: Bevacizumab can be an effective treatment of RVO-MO in a real-world setting with outcomes approaching those reported by the seminal clinical trials. The functional and anatomical outcomes of intravitreal therapy were better for BRVO than CRVO.

The Interaction of K and O2 on Au(111): Multiple Growth Modes of Potassium Oxide and Their Catalytic Activity for CO Oxidation.

In industrial catalysis, alkali cations are frequently used to promote activity or selectivity. Scanning tunneling microscopy, ambient-pressure X-ray photoelectron spectroscopy, and density-functional calculations were used to study the structure and reactivity of potassium oxides in contact with the Au(111) surface. Three different types of oxides (K2 O2 , K2 O and KOy with y<0.5) were observed on top of the gold substrate at 300-525 K. Initially, small aggregates of K2 O2 /K2 O (1-2 nm in size) were seen at the elbows of the herringbone structure. After increasing the K coverage (>0.15 ML), large islands of the oxide (20-40 nm in size) appeared. These islands contained a mixture of K2 O and KOy (y<0.5). A key correlation was found involving the structure, oxidation state, and chemical activity of the alkali oxide. The small aggregates of potassium oxide had a very high catalytic activity for the oxidation of CO, being much more than plain promoters.

Beyond the Present-Fault Paradigm: Expanding Mens rea Definitions in the General Part.

This article explores the use of mens rea terms in the criminal general part. We contend the current law fails properly to conceptualise mens rea for a large category of offences, namely bespoke/substantive inchoate offences, attempt, conspiracy, assisting and encouraging, and the general offence of complicity. These offences involve two conduct events: one in the present and one in future. However, current mens rea terms are defined as if applied to the more conventional category of criminal offence which only involves present conduct-a practice which we term the 'present-fault paradigm'. We explore the limits of current mens rea terms, defined for present-conduct targets (circumstances and results), when applied to future-conduct ulterior targets within inchoate and complicity offences. We contend that current mens rea definitions and analysis within the general part are inappropriate for targeting elements related to future conduct/offending, and we suggest more appropriate bases for conceptualising such mens rea.

Xenon Trapping in Metal-Supported Silica Nanocages.

Xenon (Xe) is a valuable and scarce noble gas used in various applications, including lighting, electronics, and anesthetics, among many others. It is also a volatile byproduct of the nuclear fission of uranium. A novel material architecture consisting of silicate nanocages in contact with a metal surface and an approach for trapping single Xe atoms in these cages is presented. The trapping is done at low Xe pressures and temperatures between 400 and 600 K, and the process is monitored in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. Release of the Xe from the cages occurs only when heating to temperatures above 750 K. A model that explains the experimental trapping kinetics is proposed and tested using Monte Carlo methods. Density functional theory calculations show activation energies for Xe exiting the cages consistent with experiments. This work can have significant implications in various fields, including Xe production, nuclear power, nuclear waste remediation, and nonproliferation of nuclear weapons. The results are also expected to apply to argon, krypton, and radon, opening an even more comprehensive range of applications.

Bi-directional tuning of thermal transport in SrCoOx with electrochemically induced phase transitions.

Unlike the wide-ranging dynamic control of electrical conductivity, there does not exist an analogous ability to tune thermal conductivity by means of electric potential. The traditional picture assumes that atoms inserted into a material's lattice act purely as a source of scattering for thermal carriers, which can only reduce thermal conductivity. In contrast, here we show that the electrochemical control of oxygen and proton concentration in an oxide provides a new ability to bi-directionally control thermal conductivity. On electrochemically oxygenating the brownmillerite SrCoO2.5 to the perovskite SrCoO3-δ, the thermal conductivity increases by a factor of 2.5, whereas protonating it to form hydrogenated SrCoO2.5 effectively reduces the thermal conductivity by a factor of four. This bi-directional tuning of thermal conductivity across a nearly 10 ± 4-fold range at room temperature is achieved by using ionic liquid gating to trigger the 'tri-state' phase transitions in a single device. We elucidated the effects of these anionic and cationic species, and the resultant changes in lattice constants and lattice symmetry on thermal conductivity by combining chemical and structural information from X-ray absorption spectroscopy with thermoreflectance thermal conductivity measurements and ab initio calculations. This ability to control multiple ion types, multiple phase transitions and electronic conductivity that spans metallic through to insulating behaviour in oxides by electrical means provides a new framework for tuning thermal transport over a wide range.

The erroneous chondrichthyan egg case assignments from the Devonian: implications for the knowledge on the evolution of the reproductive strategy within chondrichthyans.

Spiraxis interstrialis, and its junior synonym Fayolia mourloni, an uppermost Famennian (Upper Devonian) fossil first described as algae and subsequently interpreted as the oldest known chondrichthyan egg case, is reinvestigated based on the discovery of several additional specimens in Belgian collections. New data, in particular from micro-CT imaging, allow to refute S. interstrialis, and by extension also Spiraxis major (the type species of Spiraxis Newberry, non Adams) and Spiraxis randalli from the Famennian of New York and Pennsylvania, as chondrichthyan egg cases. Alternative interpretations of these enigmatic helicoidal fossils are discussed. The first occurrence of oviparity in the fossil record of chondrichthyans is thus not as old as previously thought and is close to the first occurrence of viviparity in this group, both being recognised now in the Mississippian. The question of which of both conditions is plesiomorphic within chondrichthyans, and more widely within vertebrates, is discussed. Also, the presence of the genus Spiraxis in both the USA (east coast) and Belgium reinforces the strong faunal resemblance already observed in both palaeogeographical areas. It suggests important faunal exchanges between these regions of the Euramerica landmass during the Famennian.

Strongly correlated perovskite lithium ion shuttles.

Solid-state ion shuttles are of broad interest in electrochemical devices, nonvolatile memory, neuromorphic computing, and biomimicry utilizing synthetic membranes. Traditional design approaches are primarily based on substitutional doping of dissimilar valent cations in a solid lattice, which has inherent limits on dopant concentration and thereby ionic conductivity. Here, we demonstrate perovskite nickelates as Li-ion shuttles with simultaneous suppression of electronic transport via Mott transition. Electrochemically lithiated SmNiO3 (Li-SNO) contains a large amount of mobile Li+ located in interstitial sites of the perovskite approaching one dopant ion per unit cell. A significant lattice expansion associated with interstitial doping allows for fast Li+ conduction with reduced activation energy. We further present a generalization of this approach with results on other rare-earth perovskite nickelates as well as dopants such as Na+ The results highlight the potential of quantum materials and emergent physics in design of ion conductors.

Enhanced Catalysis under 2D Silica: A CO Oxidation Study.

Interfacially confined microenvironments have recently gained attention in catalysis, as they can be used to modulate reaction chemistry. The emergence of a 2D nanospace at the interface between a 2D material and its support can promote varying kinetic and energetic schemes based on molecular level confinement effects imposed in this reduced volume. We report on the use of a 2D oxide cover, bilayer silica, on catalytically active Pd(111) undergoing the CO oxidation reaction. We "uncover" mechanistic insights about the structure-activity relationship with and without a 2D silica overlayer using in situ IR and X-ray spectroscopy and mass spectrometry methods. We find that the CO oxidation reaction on Pd(111) benefits from confinement effects imposed on surface adsorbates under 2D silica. This interaction results in a lower and more dispersed coverage of CO adsorbates with restricted CO adsorption geometries, which promote oxygen adsorption and lay the foundation for the formation of a reactive surface oxide that produces higher CO2 formation rates than Pd alone.

CO Oxidation Mechanisms on CoOx-Pt Thin Films.

The reaction of CO and O2 with submonolayer and multilayer CoOx films on Pt(111), to produce CO2, was investigated at room temperature in the mTorr pressure regime. Using operando ambient pressure X-ray photoelectron spectroscopy and high pressure scanning tunneling microscopy, as well as density functional theory calculations, we found that the presence of oxygen vacancies in partially oxidized CoOx films significantly enhances the CO oxidation activity to form CO2 upon exposure to mTorr pressures of CO at room temperature. In contrast, CoO films without O-vacancies are much less active for CO2 formation at RT, and CO only adsorbed in the form of carbonate species that are stable up to 260 °C. On submonolayer CoOx islands, the carbonates form preferentially at island edges, deactivating the edge sites for CO2 formation, even while the reaction proceeds inside the islands. These results provide a detailed understanding of CO oxidation pathways on systems where noble metals such as Pt interact with reducible oxides.

Morphology and chemical behavior of model CsOx/Cu2O/Cu(111) nanocatalysts for methanol synthesis: Reaction with CO2 and H2.

Cs is a promoter of Cu-based catalysts for the synthesis of alcohols from CO2 hydrogenation. Scanning tunneling microscopy and ambient-pressure x-ray photoelectron spectroscopy were used to study the morphology and chemical properties of surfaces generated by the deposition of cesium on Cu2O/Cu(111) and Cu(111) substrates. CsOx nanostructures were formed after Cs metal was deposited on Cu2O/Cu(111) at 300 K. The formed CsOx protrude over the surface of copper oxide by 2-4 Å, with the dimension at the base of the nanostructures being in the range of 1-3 nm. Heating to elevated temperature induced significant changes in the size and dispersion of the CsOx nanostructures, and there was a clear reconstruction of the copper oxide substrate, which then exhibited long range order with a hexagonally packed structure. The as-deposited and annealed surfaces of CsOx/Cu2O/Cu(111) were more reactive toward CO2 than plain Cu2O/Cu(111) or clean Cu(111). However, none of them were stable in the presence of H2, which fully reduced the copper oxide at 400-450 K. In CsOx/Cu(111), the CsOx nanoclusters were dispersed all over the metallic copper in no particular order. The CsOx species had an average width of 2 nm and ∼1 Å height. The CsOx/Cu(111) systems exhibited the highest activity for the binding and dissociation of CO2, suggesting that the CsOx-copper interface plays a key role in alcohol synthesis.

Catalytic Oxidation of CO on a Curved Pt(111) Surface: Simultaneous Ignition at All Facets through a Transient CO-O Complex*.

The catalytic oxidation of CO on transition metals, such as Pt, is commonly viewed as a sharp transition from the CO-inhibited surface to the active metal, covered with O. However, we find that minor amounts of O are present in the CO-poisoned layer that explain why, surprisingly, CO desorbs at stepped and flat Pt crystal planes at once, regardless of the reaction conditions. Using near-ambient pressure X-ray photoemission and a curved Pt(111) crystal we probe the chemical composition at surfaces with variable step density during the CO oxidation reaction. Analysis of C and O core levels across the curved crystal reveals that, right before light-off, subsurface O builds up within (111) terraces. This is key to trigger the simultaneous ignition of the catalytic reaction at different Pt surfaces: a CO-Pt-O complex is formed that equals the CO chemisorption energy at terraces and steps, leading to the abrupt desorption of poisoning CO from all crystal facets at the same temperature.

Projection of Long-Term Visual Acuity Outcomes Based on Initial Treatment Response in Neovascular Age-Related Macular Degeneration.

PURPOSE: To explore various methods for assessing the early response to vascular endothelial growth factor (VEGF) inhibitors for neovascular age-related macular degeneration and investigate their association with 3-year visual acuity (VA) outcomes. DESIGN: Database study, prospectively designed. PARTICIPANTS: Treatment-naïve eyes in the Fight Retinal Blindness! registry that commenced anti-VEGF therapy between January 1, 2007, and March 1, 2014, that received 3 anti-VEGF injections within the first 3 months. METHODS: The early response was defined as occurring up until the fourth injection. Various early response metrics were explored: (1) achieving good VA (≥70 letters; Snellen equivalent, 20/40), (2) absolute change in VA from baseline, (3) time to first grading of the choroidal neovascular lesion as inactive, and (4) maximum rate of VA change between successive injections. MAIN OUTCOME MEASURES: Proportion of eyes achieving ≥70 letters 3 years. RESULTS: This study included 2051 treatment-naïve eyes from 1828 patients. Achieving good vision at 3 years was associated significantly with (1) having good vision by the fourth injection (VA ≥70 vs. VA <70 letters: odds ratio [OR], 9.8; 95% confidence interval [CI], 6.5-14.7), (2) small (1-5 letters) or large (>5 letters) early VA gains (vs. early VA loss: OR, 1.8; 95% CI, 1.2-2.6; P = 0.002; and OR, 1.8; 95% CI, 1.3-2.5; P < 0.001), (3) fewer injections until first grading of lesion inactivity (≤3 vs. >3 injections: OR, 1.6; 95% CI, 1.2-2.1; P < 0.001), (4) gradual change (between -4 and 4 letters) or rapid gains (≥5 letters) between successive injections (vs. rapid loss: OR, 1.7; 95% CI, 1.1-2.6; P = 0.015; and OR, 1.6; 95% CI, 1.1-2.3; P = 0.018). Eyes that achieved small or large early gains had similar vision at 3 years (65.0 and 64.7 letters, respectively) and had better vision than eyes with early VA loss (57.2 letters). CONCLUSIONS: Attainment of good vision by the fourth injection was associated strongly with 3-year visual outcomes, whereas other early response parameters showed a moderate association. The early response during the initial 3 monthly injections can be a useful guide for subsequent treatment decisions.

The Surface Chemistry of Methanol on Pd(111) and H-Pd(111) Surfaces: C-O Bond Cleavage and the Effects of Metal Hydride Formation.

Palladium catalysts are frequently employed in processes where methanol is an energy vector or carrier, being useful for the synthesis of methanol from mixtures of carbon dioxide and hydrogen (CO2/H2) or its steam reforming on demand. Results of synchrotron-based ambient pressure X-ray photoelectron spectroscopy for the adsorption of methanol on a Pd(111) model catalyst show a rich surface chemistry and complex phenomena that strongly depend on pressure and temperature. At low pressures (<10-6 Torr) and temperatures (<300 K), CO is the dominant decomposition product. As the pressure increases, cleavage of C-H, O-H, and C-O bonds is observed, and at elevated temperatures (400-600 K) the formation of CO and CHx/C fragments compete on the surface. Thus, existing reaction networks for methanol decomposition must be modified. Furthermore, surface and subsurface hydrogen (coming from PdHx) play a significant role in the stability and removal of CHx and C species.

Initial response and 12-month outcomes after commencing dexamethasone or vascular endothelial growth factor inhibitors for retinal vein occlusion in the FRB registry.

To compare baseline characteristics, initial response and 12-month efficacy and safety outcomes in eyes with branch and central retinal vein occlusion (BRVO and CRVO) treated with dexamethasone implants (DEX) or anti-vascular endothelial growth factor (anti-VEGF) we performed a multi-centre, retrospective and observational study using Fight Retinal Blindness! Registry. Of 725 eligible eyes, 10% received DEX initially with very frequent adjunctive anti-VEGF (BRVO-DEX 49%, CRVO-DEX 60%). The primary outcome of mean adjusted change in VA at 12 months with DEX and anti-VEGF initiated groups were not statistically significantly different (BRVO: DEX + 6.7, anti-VEGF + 10.6 letters; CRVO: DEX + 2.8, anti-VEGF + 6.8 letters). DEX initiated eyes had fewer injections and visits than anti-VEGF initiated eyes. The BRVO-DEX eyes had greater initial mean changes in VA and central subfield thickness (CST) and achieved inactivity sooner than BRVO-anti-VEGF eyes. The mean CST after the first three months was above 350 µm in all but the BRVO-anti-VEGF group, suggesting undertreatment. In routine care DEX is uncommonly used when available as initial treatment of BRVO and CRVO requiring supplemental anti-VEGF within the first year. The 12-month outcomes were similar, but DEX initiated eyes had fewer injections and visits but more episodes of raised IOP Vs those starting anti-VEGF.

European Unmet Needs in the Management of Neovascular Age-Related Macular Degeneration in Daily Practice: Data from the Fight Retinal Blindness! Registry.

PURPOSE: To evaluate the proportion, predictors, and outcomes of patients with neovascular age-related macular degeneration (nAMD) treated with a high burden of VEGF inhibitor intravitreal (IVT) injections after 2 years in routine clinical practice. DESIGN: Retrospective analysis of data from a prospectively designed observational outcomes registry, the Fight Retinal Blindness! Project, of patients treated in European centers. PARTICIPANTS: Treatment-naïve eyes (1 eye per patient) starting VEGF inhibitors for nAMD from January 2017 to March 2020 with 24 months of follow-up. We analyzed the following 3 treatment-burden groups defined by the mean interval of the 3 closest injections to the 24-month visit: (1) those with a high-treatment burden had injection intervals ≤ 42 days, (2) those with a low-treatment burden had injection intervals between 43 and 83 days; and (3) those with tolerable treatment burden had injection intervals between 84 and 365 days. METHODS: Multinomial regression was used to evaluate baseline risk predictors of patients requiring a high-treatment burden. MAIN OUTCOME MEASURES: The proportion of patients that experienced a high-treatment burden at 2 years and its predictors. RESULTS: We identified 2038 eligible patients completing 2 years of treatment (2038/3943 patients [60%]) with a median (quartile 1, quartile 3) of 13 (10, 17) injections. The proportion of patients with a high-treatment burden was 25% (516 patients) at 2 years. Younger patients (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.96-0.99; P < 0.01) were more likely to have high-treatment burden, whereas eyes with type 3 choroidal neovascular lesions at baseline were significantly less likely (OR, 0.26; 95% CI, 0.13-0.52; P < 0.01). Regarding type of fluid, patients with subretinal fluid only at baseline (OR, 3.85; 95% CI, 1.34-11.01; P = 0.01) and persistent active intraretinal (OR, 1.56; 95% CI, 1.18-2.06; P < 0.01) or subretinal fluid only (OR, 2.21; 95% CI, 1.52-3.21; P < 0.01) after the loading phase had a higher risk of high treatment burden at 2 years. CONCLUSIONS: High treatment burden is a common issue in routine clinical practice in Europe, with a quarter of patients requiring injections of conventional VEGF inhibitors every 6 weeks at 2 years and 40% discontinuing treatment within 2 years. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Three-Year Outcomes of VEGF Inhibitors in Naive Branch Retinal Vein Occlusion: Fight Retinal Blindness!

PURPOSE: To evaluate the 3-year outcomes of VEGF inhibitors in the treatment of cystoid macular edema due to branch retinal vein occlusion (BRVO) in an international multicenter cohort of eyes. DESIGN: Multicenter, international, BRVO database study. SUBJECTS: Seven hundred forty-seven patients (760 eyes) undergoing intravitreal therapy for BRVO for 3 years in a multicenter international setting. METHODS: Demographics, visual acuity (VA) in logarithm of the minimum angle of resolution letters, central subfield thickness (CST), treatments, number of injections, and visits data was collected using a validated web-based tool. MAIN OUTCOME MEASURES: Visual acuity gain at 3 years in logarithm of the minimum angle of resolution letters. Secondary outcome measures included anatomical results, treatment pattern, and percentage of completers. A subgroup analysis by study drug was conducted for clinical outcomes. RESULTS: Mean adjusted VA change was +11 letters (95% confidence interval 9-13), mean adjusted change in CST was -176 µm (-193, -159). Median number of injections/visits was 16 of 24 at 3 years of follow-up. Most eyes received VEGF inhibitors exclusively (89%, n = 677) and as a monotherapy in 71% (n = 538). Few eyes were switched to steroids (11%, n = 83). Suspensions in treatment >180 days occurred in 26% of study eyes. Aflibercept showed greater CST reductions (-147 vs. -128 vs. -114 µm; P < 0.001) and significantly lower switching rates (14% vs. 38% vs. 33%; P < 0.001) compared with ranibizumab and bevacizumab, respectively. CONCLUSIONS: This international study of 3-year BRVO outcomes after starting treatment with VEGF inhibitors found adequate visual and anatomical results in routine clinical care. Visual outcomes were similar among the different initiating VEGF inhibitors, although eyes starting with aflibercept had better anatomical outcomes and a lower switching rate. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Morphology Dependent Reactivity of CsOx Nanostructures on Au(111): Binding and Hydrogenation of CO2 to HCOOH.

Cesium oxide (CsOx) nanostructures grown on Au(111) behave as active centers for the CO2 binding and hydrogenation reactions. The morphology and reactivity of these CsOx systems were investigated as a function of alkali coverage using scanning tunneling microscopy (STM), ambient pressure X-ray photoelectron spectroscopy (AP-XPS), and density functional theory (DFT) calculations. STM results show that initially (0.05-0.10 ML) cesium oxide clusters (Cs2O2) grow at the elbow sites of the herringbone of Au(111), subsequently transforming into two-dimensional islands with increasing cesium coverage (>0.15 ML). XPS measurements reveal the presence of suboxidic (CsyO; y ≥ 2) species for the island structures. The higher coverages of cesium oxide nanostructures contain a lower O/Cs ratio, resulting in a stronger binding of CO2. Moreover, the O atoms in the CsyO structure undergo a rearrangement upon the adsorption of CO2 which is a reversible phenomenon. Under CO2 hydrogenation conditions, the small Cs2O2 clusters are hydroxylated, thereby preventing the adsorption of CO2. However, the hydroxylation of the higher coverages of CsyO did not prevent CO2 adsorption, and adsorbed CO2 transformed to HCOO species that eventually yield HCOOH. DFT calculations further confirm that the dissociated H2 attacks the C in the adsorbate to produce formate, which is both thermodynamically and kinetically favored during the CO2 reaction with hydroxylated CsyO. These results demonstrate that cesium oxide by itself is an excellent catalyst for CO2 hydrogenation that could produce formate, an important intermediate for the generation of value-added species. The role of the alkali oxide nanostructures as active centers, not merely as promoters, may have broad implications, wherein the alkali oxides can be considered in the design of materials tuned for specific applications in heterogeneous catalysis.