Fan Zhang

The (0001) crystal facet of β-Co(OH)₂ has been widely accepted as an inert facet for the oxygen evolution reaction (OER), while the (101̅0) facet is considered more active. However, mechanistic details regarding the origin of the differences at the coordination environment and the electronic state level remain unexplored to date. Herein, we used a multimode optical imaging method to track the evolving heterogeneous dynamics of cobalt species during the OER process and correlate it with the OER performance. Cobalt underwent the oxidation to Co_Oh³⁺, distorted to Co_Td³⁺, and subsequently oxidized to Co_Td⁴⁺, in which the distribution was mapped by vis-absorption imaging. It indicates that cobalt was negligibly oxidized to Co_Td⁴⁺ on the (0001) facet, because of the coordination-saturated environment, while it was relatively facile on the (101̅0) facet. The adsorbate evolution mechanism (AEM) process and lattice-oxygen-mediated mechanism (LOM) process during OER were spatiotemporally decoupled by electrochemiluminescence (ECL) imaging. Furthermore, the cobalt oxidation kinetics was tailored by the atom topping (Fe/Ni) strategy, which was accelerated by iron doping and retarded by nickel doping. On this basis, we propose a lattice O_v-involved mechanism for transforming Co_Oh³⁺ to Co_Td³⁺, which is a crucial step to Co_Td⁴⁺. The accelerated oxidation kinetics is from the enrichment of O_v, which induces abundant coordination-unsaturated cobalt, facilitating the transformation to Co_Td^3+/4+. This study examined the oxidation kinetics of cobalt with high spatiotemporal resolution and further tailors the distribution of Co_Td⁴⁺, which is expected to promote future research on the kinetic tuning of crystal facets.

Protein-based therapeutics have been developed to treat a range of conditions and assays use immobilized capture proteins for the detection of diseases. A challenge in the development of protein-based products is maintaining the protein in the folded state during processing and storage. The most common method of stabilizing proteins for storage is lyophilization. However, the freeze-drying process remains expensive and many proteins that are lyophilized must be refrigerated or frozen to maintain functionality. Cold storage strategies can be challenging for the transportation of protein-based products and can be difficult or impossible in low resource settings. Recent research has demonstrated that anhydrous, or dry state, preservation in a trehalose amorphous solid matrix offers an alternative to freeze drying for the preservation of biologics. We have previously described a new processing technique, light assisted drying (LAD), to create trehalose preservation matrices. LAD uses illumination by near-infrared laser light to selectively heat water and speeds dehydration of small volume (40 μL) samples. Low end moisture contents (EMC’s) are necessary for storage at supra-zero temperatures and this low water content must be uniform to insure successful long-term storage of embedded biologics. Our previous work has demonstrated the ability of LAD to reach EMCs necessary for storage at elevated temperatures. In this work, Raman spectroscopy is used to assess the trehalose distribution and water content across LAD processed samples. Results indicate that the water content of LAD process samples is uniform. LAD is a promising technique for processing biologics in preparation for anhydrous storage.

Compared with the large variety of solid gold nanostructures, synthetic approaches for their hollow counterparts are limited, largely confined to chemical and irradiation‐based etching of preformed nanostructures. In particular, the preparation of through nanopore structures is extremely challenging. Here, a unique strategy for direct synthesis of gold nanopores in solution without the need for sacrificial templates or postsynthesis processing is reported. By controlling the degree of crystal screw dislocation, a single through pore with diameter ranging from sub‐nanometer to tens of nanometers, in the center of large gold nanoplates, can be engineered with precision. Ionic current rectification behaviors are observed using the gold nanopore, potentially enabling new capabilities in biosensing, sequencing, and imaging.