Chia-Ying Chiang

Hydration structures govern the properties and functions of hydrogels, yet selectively measuring hydration water in the presence of abundant bulk water remains analytically challenging. Here we applied pressure‐controlled attenuated total reflection infrared spectroscopy (ATR‐IR) combined with multivariate curve resolution (MCR) analysis, a method established in our previous work, to selectively characterize the hydration water of poly(2‐hydroxyethyl methacrylate) (PHEMA)‐based hydrogels containing poly(ethylene glycol) (PEG) or poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC). Controlled pressure applied to the gels on the ATR prism yielded spectral datasets with systematically varying bulk‐to‐hydration water ratios, which were decomposed by MCR. The resolved spectra showed that increasing PEG content decreased the intensity near 3200 cm ⁻¹ , indicating enhanced polymer–water interactions that disrupt the hydrogen‐bond network of neighboring water. In contrast, PMPC increased the population of tetrahedrally coordinated water, indicating that it preserves the bulk‐like hydrogen‐bond network. The ν(O–H)/ν(C–H) area ratio further showed that PMPC‐containing hydrogels retain more hydration water than their PEG counterparts at equivalent compositions. The resolved hydration water is discussed in relation to the nonfreezing, intermediate and free water populations defined by calorimetry and NMR, and pressure‐induced dehydration is interpreted as an osmotic and poroelastic response of the network. These findings provide molecular‐level insight into the distinct hydration behaviors of PEG and PMPC, offering a mechanistic rationale for the superior lubricity of PMPC‐based soft contact lens materials.

Both antibiofouling nonionic and zwitterionic self-assembled monolayers (SAMs) resist protein and cell adhesion similarly, despite having different chemical structures. This work elucidates their antibiofouling mechanisms by integrating surface force measurements with atomic force microscopy (AFM) and surface-enhanced infrared absorption (SEIRA) spectroscopy. The findings show that a very thin (4 nm) water layer on nonionic hydroxy-terminated tri(ethylene glycol) (EG3-OH) SAMs results in long-range repulsion. SEIRA spectroscopy identified different hydrogen-bonding states in interfacial water: intense interactions with SB groups and weaker bonds with EG3-OH groups. These SEIRA insights clarify the nature of surface forces influenced by interfacial water. The study discusses how variations in hydration, SAM-water interfacial interactions, and the role of interfacial water molecules contribute to the antibiofouling effectiveness of these two SAM types.

Modulating the crystal phase of a photocatalyst significantly impacts its surface and photochemical properties, allowing for the adjustment of catalytic activity and selectivity, particularly in the electrooxidation reactions of biomass-derived chemicals. Herein, monoclinic and hexagonal phases of WO₃ are employed as photoanodes for the photoelectrochemical conversion of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF). The monoclinic phase demonstrated exceptional performance in photoelectrocatalytic HMF oxidation, achieving remarkable photocurrent densities (1.1 mA cm^-2), which were 5.5 times greater than those observed for hexagonal WO₃. Moreover, the yield of DFF products obtained over monoclinic WO₃ was approximately 2.5 times higher compared to that of hexagonal WO₃. A combination of experiments and theoretical calculations indicates that the superior performance of monoclinic WO₃ for HMF oxidation mainly originates from enhanced light harvesting efficiency, better charge separation and utilization, balanced adsorption energy, and stronger oxidative ability of photogenerated holes. This study emphasizes the potential of crystal phase engineering to regulate the reaction activity and selectivity and provides insights into how to design next-generation high-performance photoelectrodes for sustainable chemical production from biomass.

In this work, we report for the first time a comprehensive operando investigation of the intricate correlation between dynamic phase evolution and glycerol electrooxidation reaction (GEOR) performance across three primary MnO₂ crystallographic phases (α-, β-, and γ-MnO₂). The results showed that all three electrocatalysts exhibited comparable selectivity toward three-carbon products (∼90%), but γ-MnO₂ exhibited superior performance, with a low onset potential of ∼1.45 V_RHE, the highest current density of ∼1.9 mA cm^-2 at 1.85 V_RHE, and reasonable stability. Operando Raman spectroscopy revealed the potential-induced surface reconstruction of different MnO₂ structures from which a correlation among the applied potential, electrocatalytic activity, and product distribution was identified. The higher the applied potential, the greater conversion from the original structure to δ-MnO₂, resulting in lower C-C cleavage and higher 3C product selectivity. This study not only provides a systematic understanding of structure-controlled electrocatalytic activity for high selectivity toward 3C products of MnO₂ but also contributes to the development of a non-noble and environmentally friendly catalyst for valorizing glycerol.

Efficient glycerol electrooxidation reaction (GEOR) over gold@nickel sulfide (Au@NiS_x) yolk@shell nanostructures is demonstrated, achieving ≈50.4% glycerol conversion at 10 h, 92.6% selectivity toward three‐carbon products, and 90.7% total Faradaic efficiency. By regulating the electrode potential, tartronic acid (TART), one of the highest value‐added intermediates, can be produced with a selectivity as high as 43.1% and a yield of 45.6 µmol cm⁻² h⁻¹. A combination of ex situ microstructural analysis, operando Raman, and operando X‐ray absorption measurements reveals a dynamic surface reconstruction course from Au@NiS_x to Au@NiS_x/NiOOH during the glycerol oxidation process. The unique reconstructed architectures featuring conductive interior NiS_x components and active surface high‐valence Ni³⁺ species account for the superior GEOR performance. Further integration of GEOR with hydrogen evolution reaction is realized by employing Au@NiS_x as both anode and cathode electrocatalysts in a two‐electrode configuration. Concomitantly production of TART and hydrogen fuel is accomplished. This study demonstrates that Au@NiS_x not only can convert glycerol to TART with remarkable efficiency and selectivity, but also can produce hydrogen at a moderate level. The findings from this study can facilitate the development of dual‐functional electrocatalysts capable of producing high‐value products at both the cathode and anode sides.

In the present work, we explored an economically feasible and environmentally friendly attempt to achieve tunable wettability of ceramic carbon substrates applicable in water splitting devices. It was found that by rationally controlling the surface functional groups, ceramic carbon substrates with different surface hydrophilicities, electroactive surface areas, and electrochemical behaviors could be achieved. Particularly, a hydrophilic ceramic carbon electrode (CCE) was obtained by using tetramethoxysilane as the modifier, which allowed uniform anchoring of an amorphous molybdenum sulfide (MoS_x) hydrogen evolution electrocatalyst on its surface through a simple chemical vapor deposition method. The optimized CCE/MoS_x exhibited promising hydrogen evolution reaction activity and good stability, with a small onset overpotential (∼250 mV) and a low Tafel slope (58 mV dec⁻¹). The CCE/MoS_x catalyst also showed reasonable stability under acidic conditions. Such promising electrochemical performance has been attributed to the strong chemical and electronic coupling between the conducting CCE and MoS_x. This work paves a new way for the rational design and fabrication of an efficient composite electrode by selecting ceramic carbon as a durable high-conductivity substrate and the collaborative optimization of the catalyst and the substrate to achieve higher hydrogen evolution performance.