Distinguishing Protein Chemical Topologies Using Supercharging Ion Mobility Spectrometry-Mass Spectrometry

A technique combining ion mobility spectrometry-mass spectrometry (IMS-MS) and supercharging electrospray ionization (ESI) has been demonstrated to differentiate protein chemical topology effectively. Incorporating as many charges as possible into proteins via supercharging ESI allows the protein chains to be largely unfolded and stretched, revealing their hidden chemical topology. Different chemical topologies result in differing geometrical sizes of the unfolded proteins due to constraints in torsional rotations in cyclic domains. By introducing new topological indices, such as the chain-length-normalized collision cross-section (CCS) and the maximum charge state (z_M) in the extensively unfolded state, we were able to successfully differentiate various protein chemical topologies, including linear chains, ring-containing topologies (lasso, tadpole, multicyclics, etc.), and mechanically interlocked rings, like catenanes.     

Subsurface Engineering Induced Fermi Level De-pinning in Metal Oxide Semiconductors for Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water splitting is a promising approach for renewable solar light conversion. However, surface Fermi level pinning (FLP), caused by surface trap states, severely restricts the PEC activities. Theoretical calculations indicate subsurface oxygen vacancy (sub-O_v) could release the FLP and retain the active structure. A series of metal oxide semiconductors with sub-O_v were prepared through precisely regulated spin-coating and calcination. Etching X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and electron energy loss spectra (EELS) demonstrated O_v located at sub ∼2–5 nm region. Mott–Schottky and open circuit photovoltage results confirmed the surface trap states elimination and Fermi level de-pinning. Thus, superior PEC performances of 5.1, 3.4, and 2.1 mA cm⁻² at 1.23 V vs. RHE were achieved on BiVO₄, Bi₂O₃, TiO₂ with outstanding stability for 72 h, outperforming most reported works under the identical conditions.     

Molecular Recognition Regulates Coordination Structure of Single-Atom Sites

Coordination engineering for single-atom sites has drawn increasing attention, yet its chemical synthesis remains a tough issue, especially for tailorable coordination structures. Herein, a molecular recognition strategy is proposed to fabricate single-atom sites with regulable local coordination structures. Specifically, a heteroatom-containing ligand serves as the guest molecule to induce coordination interaction with the metal-containing host, precisely settling the heteroatoms into the local structure of single-atom sites. As a proof of concept, thiophene is selected as the guest molecule, and sulfur atoms are successfully introduced into the local coordination structure of iron single-atom sites. Ultrahigh oxygen reduction electrocatalytic activity is achieved with a half-wave potential of 0.93 V versus reversible hydrogen electrode. Furthermore, the strategy possesses excellent universality towards diversified types of single-atom sites. This work makes breakthroughs in the fabrication of single-atom sites and affords new opportunities in structural regulation at the atomic level.