Yifan Li

The origins of activity hysteresis during heating and cooling stages in CO oxidation are still heavily debated. Pt-CeO2 and Pt-Al2O3 were observed to display completely different hysteresis phenomena. Pt-Al2O3 exhibited normal behavior, while Pt-CeO2 showed inverse hysteresis. The affecting issues of initial Pt nanoparticle size, mass and heat transfer limitations, and local overheating were all excluded for both catalysts. By using operando and in situ characterization technologies, kinetic analyses, density functional theory (DFT) calculations, as well as ab initio molecular dynamics (AIMD) simulations, the nature of thermal hysteresis was revealed. The different interactions between the metal and supports induced different dynamic oxidation behaviors and morphology evolutions of Pt during the heating and cooling reactions, which are the root causes. Pt in Pt-CeO2 suffered irreversible oxidation mainly driven by reverse oxygen spillover and formed PtxOy ensemble which displays poorer activity. In contrast, Pt in Pt-Al2O3 underwent structural collapse and dispersion on Al2O3 surface at high temperature, and oxygen spillover to support preserved the initial chemical state of Pt.

Pt-CeO2 is highly active for CO oxidation but suffers rapid deactivation due to the oxidation of Pt nanoparticles into less-active PtOx. Here, we introduce H2 into the CO oxidation feed gas to dynamically stabilize Pt in its metallic state. The H2/CO ratio is critical at an optimal ratio of 2, adding H2 significantly enhances both activity and durability, with complete CO conversion maintained for more than 110 h at 95 °C over 2Pt-CeO2, while it only kept 0.4 h under H2-free condition. In-situ infrared spectroscopy, near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), and density functional theory (DFT) calculations reveal that H2 does not merely consume O2; it preferentially reacts with the coordinated oxygen in PtOx species, thereby preserving metallic Pt throughout the reaction. This work demonstrates a dynamic gas-phase strategy to overcome the activity-stability tradeoff in Pt-CeO2 catalysts.

Owing to the synergistic effect of hetero-materials and the improvement of the oxygen vacancy (VO) concentration, construction of heterostructural materials represents an effective strategy for developing highly sensitive sensors for trace formaldehyde detection. However, the traditional sensing mechanism neglects the role of lattice oxygen (OLat). Moreover, conventional characterizations often fail to identify the specific component of the composite that is responsible for providing reactive OLat. Herein, we report a high-performance formaldehyde sensor based on SnO2/NiO heterostructures, exhibiting an exceptional response (ΔI/Iair = 8.75 @ 1 ppm), an ultralow detection limit (4 ppb), and high selective coefficients (SF/SOthers) ranging from 49 to 533.5. Through in situ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) calculations, we present direct experimental evidence that the OLat of NiO within the SnO2/NiO heterostructure actively participates in the sensing process. Furthermore, we elucidate the underlying mechanism, demonstrating that the participation of OLat plays a significant role in enhancing the sensor's response value. This study advances the fundamental understanding of gas-sensing mechanisms based on heterostructures.

Weak intermolecular forces are ubiquitous in chemistry, materials science, and biology, yet their direct role in gas-solid interfacial phenomena has remained elusive. Here, we show that under millibar-range H₂O vapor at room temperature, monolayer Au nanoislands on Au(111) undergo pronounced restructuring within seconds through particle migration, coalescence, and Ostwald ripening. The driving force of these rapid dynamics is identified as van der Waals interaction between H₂O molecules and surface Au atoms via dipole-dipole attraction. This effect is reinforced by the formation of transient H₂O-adsorbed Au adatom complexes, which lower the energy barrier for atomic detachment and migration. Our findings provide direct atomic-level evidence that weak physical interactions alone can reshape metal nanostructures, offering a new route to engineer the surface architectures under mild conditions.

The electrosynthesis of hydrogen peroxide (H₂O₂), with renewable electricity, air, and water as inputs, offers a sustainable alternative to the conventional anthraquinone process. Performing H₂O₂ electrosynthesis in concentrated acid offers advantages in functionality and energy efficiency over alkaline media yet is currently limited by short longevity. Here, we first investigate the origins of performance loss of oxidized carbon, a proven catalyst for H₂O₂ electrosynthesis, and observe its gradual reduction to pristine carbon during acidic electrolysis. This inspires us to design a catalyst that can stabilize the oxidized carbon sites via strong Y-O-C coordination─a strategy we instantiate via carbon-caged-yttria (C@Y₂O_x) catalysts. In acids, the C@Y₂O_x catalyst sustains a H₂O₂ selectivity of 97% after 10,000 cycles. Integrated into a gas diffusion electrode and operated in concentrated acids of pH < 0, the C@Y₂O_x catalyst delivers a partial current density of ∼100 mA cm^-2 at -0.4 V versus RHE over 100 h in a flow cell. Using quasi in situ NAP-XPS, operando FT-IR, and theoretical calculations, we elucidate that coordination with yttrium energetically suppresses the breakage of the O-C bond and accordingly preserves the oxidized carbon sites for selective and long-term electrosynthesis of H₂O₂.