Tao Gao

Electrochemical oxidation is typically regarded as incompatible with hydrogen intermediate formation, particularly at highly positive potentials where surface hydrogen species are expected to be rapidly oxidized. Formaldehyde oxidation reaction (FOR) on palladium represents a prominent example: low-potential FOR has been associated with hydrogen generation, whereas high-potential FOR is commonly interpreted as a direct two-electron oxidation to formate that bypasses hydrogen intermediates. Here we challenge this conventional view using a Janus palladium membrane electrode (J-Pdm) that spatially decouples hydrogen generation, absorption, permeation, and detection. By monitoring the hydrogen oxidation reaction (HOR) current on the electrochemically isolated detection side of J-Pdm, we directly quantify hydrogen atoms generated during FOR under alkaline conditions. Unexpectedly, permeated hydrogen remains detectable over a broad FOR potential window up to 1.5 V vs RHE (reversible hydrogen electrode), demonstrating that high-potential FOR on Pd is not a hydrogen-free oxidation process. Coulometric measurements confirm hydrogen uptake within the Pd lattice, with H/Pd ratios reaching up to 0.57. Spectroscopic and computational results support a sequential hydrogen-generating oxidation mechanism in which formaldehyde-derived intermediates undergo favorable C–H activation, while the resulting hydrogen atoms compete among absorption into the Pd lattice, recombination to H2, and oxidation to protons. FOR-generated hydrogen atoms can be utilized for styrene hydrogenation in an organic phase, establishing anodic hydrogenation as a viable electrosynthetic strategy. These findings provide new mechanistic understanding of formaldehyde oxidation on palladium and also demonstrate J-Pdm as a powerful platform for detecting and utilizing transient hydrogen intermediates in anodic reactions.

Heavy polar molecules play a central role in precision measurements that probe physics beyond the Standard Model, most notably searches for the electron electric dipole moment (eEDM). Recent demonstrations of evaporative cooling of molecular anions have created an unexplored opportunity for extending such measurements to a new class of chemical species. Here, we present the comprehensive relativistic electronic structure investigation of a heavy molecular anion FrF−, which is anticipated to be a promising candidate for laser cooling and for studies of conjugation and parity violation. Using high-level two-component configuration–interaction methods, we carried out a detailed investigation of the cooling cycle mechanism of the FrF− molecular anion and evaluated the key parameters—effective electric field (Eeff), hyperfine constant (A‖), electron–nucleon scalar–pseudoscalar constant (WP,T), and nuclear quadrupole moment constant (WM). By quantitatively disentangling the contributions from basis-set hierarchy, electron correlation, spin–orbit coupling, and quantum electrodynamics effects, we provide a transparent and reliable uncertainty analysis for each constant. Our results reveal that FrF− exhibits a remarkably large intrinsic sensitivity to the eEDM, rivaling leading neutral and cationic candidates. These findings establish ultracold molecular anions as a powerful and previously untapped platform for next-generation symmetry tests and precision measurement science.

Ammonia (NH₃) is a promising carbon-free hydrogen carrier, but lowering the temperature required for its catalytic decomposition to produce H₂ remains a challenge. The main obstacle is the strong adsorption of nitrogen (N) on the active sites, which can remain on the catalysts' surface and lead to poisoning. Using first-principles calculations, we investigate the effects of N accumulation on Fe₆ clusters during NH₃ decomposition and aim to develop strategies to mitigate N poisoning. Graphene-supported Fe₆ clusters mitigate N poisoning by reducing Fe–N interaction strength, thereby improving NH₃ decomposition efficiency. The energy barriers of the graphene-supported Fe₆N_x (x = 1, 2) clusters’ rate-limiting step have been reduced below 2 eV, compared to those calculated for the pure Fe₆ cluster (2.08 eV) and the graphene-supported Fe₆ cluster (2.53 eV). The rate-limiting step involves the Fe 3d–N 2p hybridization, during which an adsorbed N atom migrates across the Fe–Fe bond and combines with another N atom to form N₂. This study provides new insights into the potential application of graphene-supported metal catalysts for NH₃ decomposition.

High-level multireference configuration interaction plus Davidson correction (MRCI + Q) calculation method was employed to determine the potential energy curves (PECs) of 10 Λ-S states, which come from the first and second dissociation channels of the SbP molecule, as well as 34 Ω states considering the spin-orbit coupling (SOC) effect. By solving the Schrödinger equation for nuclear motion, spectroscopic constants for the ground state X¹Σ⁺ and low-lying excited states were obtained and compared with experimental data. The excellent agreement indicates the reliability of our calculations. Additionally, the calculated spin-orbit (SO) matrix elements of the 1³Π and 1⁵Π states with other Λ-S states were analyzed, and the majority of the values in the Franck-Condon region exceed 200 cm^-1, indicating strong interactions between these states. What's more, the joint effects of spin-orbit coupling and avoided crossing were discussed in detail, leading to the complex potential energy curves and double-well phenomena observed in the Ω states. Taking forbidden transitions into account, transition dipole moments with the SOC effect are considered. The Franck-Condon factors, Einstein coefficients, and radiative lifetimes for the 1³Σ⁺₁ ↔ X¹Σ⁺₀₊ transition were obtained. Analysis indicates that direct laser cooling of SbP is inappropriate.

We present a first-principles density functional theory with the Coulomb interaction U (DFT + U) investigation of the bulk properties, including structural, energetic, electronic, and mechanical properties for uranium–americium mixed oxides (U, Am)O₂. The various Am aggregation contents were investigated to better understand the impact of Am on the nuclear fuel UO₂. The supercell defect models at different scales were used to describe the solid solution (U, Am)O₂. The obtained results show that different contents of Am aggregation have a significant impact on the volume and energy of the formation of mixed oxide systems. The results of the electronic structure calculations exhibit no bandgap owing to the mixing of UO₂ and AmO₂. The mixing enthalpy of the Am aggregation systems is used to describe the phase stability of the solid solution. In particular, the mixing enthalpy of (U, Am)O₂ is significantly reduced as the Am content increases. The elastic properties of the (U, Am)O₂ mixed oxides have also been compared as a function of the Am content. Moreover, the impacts of the whole Pu aggregation content range on the bulk properties for the (U, Pu)O₂ mixed oxides are also discussed.