Physical Chemistry Chemical Physics最新文献

Phosphomolybdic acid (PMA)-based single-atom catalysts (SACs) are promising for the oxygen evolution reaction (OER), but the role of their ubiquitous carbon support has rarely been investigated. Using density functional theory (DFT), we systematically investigated the OER on TM₁/PMA (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt; PMA = [PMo₁₂O₄₀]^3-) with no support, a pristine carbon support, a hydroxyl (-OH)-functionalized support, and a carboxyl (-COOH)-functionalized support. We found that the mere presence of carbon support strongly modulates catalytic activity, an effect that far outweighs that of its subsequent functionalization. Bader charge analysis reveals significant electron donation from the carbon support to the TM₁/PMA unit, markedly altering intermediate adsorption free energies, which in turn either improves or worsens OER performance by shifting the metals along the descriptor axis and slightly lowering the volcano apex. For example, the Ni₁/PMA@C achieves a low overpotential of 0.37 V, markedly lower than 0.70 V for bare Ni₁/PMA. This support-induced modulation carries a critical methodological implication: for single-metal-on-anion SAC systems such as PMA-based catalysts, the carbon support must be explicitly included in theoretical models to capture its essential charge transfer with SAC. The carbon support is far from an inert scaffold but is a key factor in designing high-efficiency PMA-based single-atom OER catalysts.

The perovskite layer is the core component of perovskite solar cells (PSCs), and the quality of the perovskite film critically impacts the performance of PSCs. Interfacial contact optimization, defect passivation, and energy level alignment regulation are effective approaches to fabricate high-performance PSCs. Herein, an organic small molecule, 5-bromopyridine-2,3-dicarboxylic acid (BPDCA), is doped into a perovskite precursor solution to serve as the photosensitive layer of PSCs. Density functional theory (DFT) simulations and systematic characterizations confirm that BPDCA can optimize the crystallization quality of the perovskite and passivate defects in the perovskite film through the N atom on the pyridine ring and the O atom on the carboxyl group. Meanwhile, BPDCA doping optimizes the energy level matching, promotes the extraction and transport of charges, and enhances the open-circuit voltage (V_oc). The PSCs fabricated with BPDCA doping achieve a power conversion efficiency (PCE) of 20.75%, with a V_oc of 1.13 V. The unencapsulated device maintains more than 90% of the initial PCE after 1000 h of exposed storage in an air atmosphere. This work offers a straightforward and effective strategy for obtaining efficient and stable PSCs through functionalized perovskites.

Although akamptisomerism has been observed only in B-O-B-bridged macrocycles, this study shows that macrocyclic constraint is unnecessary. B-O-B linkages can undergo bond-angle inversion with a relatively low energetic cost, in contrast to analogous ethers. Walsh and NBO analyses reveal that the distinct electronic response of the B-O-B framework to angular deformation facilitates access to the nearly linear higher-order saddle point.

The presence of surfactants has a strong influence on the properties of interfaces of aqueous solutions with air and is thus of importance for a better understanding of processes involving liquid-vapor interfaces in the environment, atmosphere, and in industrial applications. The most widely used method to quantify the density of surfactants at the interface is the measurement of surface tension. Even though this is an indirect way to determine the surface concentration of surfactant molecules, surface tension measurements have provided a wealth of information for more than a century. Over the past decade, X-ray photoelectron spectroscopy (XPS) has established itself as a direct method to investigate the properties of liquid-vapor interfaces, including the concentration of ions and surfactants in the interface region. Here we compare the results of surface tension and XPS measurements on the example of n-alkane sulfonates with aliphatic chain lengths from 0 to 9 carbons. Our results show that for monodisperse systems, as those here under study, there is good quantitative agreement between the surface coverages obtained from surface tension measurements and those determined using XPS.