Chemical Science Program

Understanding the correlation between the structural evolution of electrocatalysts and their catalytic activity is both essential and challenging. In this study, we investigate this correlation in the context of the oxygen evolution reaction (OER) by examining the influence of structural disorder during/after the dynamic structural evolution on their OER activity of Fe-Ni (oxy)hydroxide catalysts using operando X-ray absorption spectroscopy, alongside other experiments and theoretical calculations. The Debye-Waller factors obtained from extended X-ray absorption fine structure analyses reflect the degree of structural disorder and exhibit a robust correlation with the intrinsic OER activities of the electrocatalysts. Enhanced OER activity of in-situ generated metal (oxy)hydroxides derived from different pre-catalysts is linked to increased structural disorder, offering a promising approach for designing efficient OER electrocatalysts. This strategy may inspire similar investigations in related electrocatalytic energy-conversion systems.

Activating O–H bonds in β,γ-unsaturated oximes is challenging due to high redox potential. Our method combines HAT and photoredox catalysis to allow the synthesis of diverse heterocycles using various radical acceptors. Mechanistic studies support the HAT process in O–H bond activation.

Precise control of exciton confinement in metal halide perovskites is critical to the development of high-performance, stable optoelectronic devices. A significant hurdle is the swift completion of ionic metathesis reactions, often within seconds, making consistent control challenging. Herein, the introduction of different steric hindrances in a Cs+sublattice within CsYb2F7is reported, which effectively modulates the reaction rate of Cs+with lead(Pb2+) and halide ions in solution, extending the synthesis time for perovskite nanostructures to tens of minutes. Importantly, the Cs+sublattice provides a crystal facet-dependent preference for perovskite growth and thus, exciton confinement, allowing the simultaneous occurrence of up to six emission bands of CsPbBr3. Moreover, the rigid CsYb2F7nano template offers high activation energy and enhances the stability of the resulting perovskite nanostructures. This methodology provides a versatile approach to synthesizing functional heterostructures. Its robustness is demonstrated byin-situ growth of perovskite nanostructures on Cs+-mediated metal-organic frameworks.

Persistent covalent-organic framework (COF) radicals hold important applications in magnetics and spintronics; however, their facile synthesis remains a daunting challenge. Here, three p-phenylenediacetonitrile-based COFs (named CityU-4, CityU-5, and CityU-6) were synthesized. Upon heat treatment (250 °C for CityU-4 and CityU-5 or 220 °C for CityU-6), these frameworks were brought into their persistent radical forms (no obvious changes after at least one year), together with several observable factors, including color changes, red-shifted absorption, the appearance of electron spin resonance (ESR) signals, and detectable magnetic susceptibility. The theoretical simulation suggests that after heat treatment, lower total energy and nonzero spin density are two main factors to guarantee persistent COFs radicals and polarized spin distributions. This work provides an efficient method for the preparation of persistent COF radicals with promising potentials.

An exciting emerging field involves extracting photon energy in a hybrid plasmonic nanostructure across an interface, converting it into other energy forms like chemical and electrical energies. However, a fundamental understanding of the design rationale and the underlying logic behind hybrid plasmonic heterostructuring, as well as a general strategy to manipulate the efficiency of hot-carrier generation, transfer, and utilization at the microscale or even atomic level, is currently lacking. To address this gap, we propose a new logic for hot-carrier energy harvesting in a plasmonic-metal/molecule hybrid system through microfaceting. It enables us to engineer metal-adsorbate-hybridized interfacial states in terms of both energy gap opening and permissible electronic excitations. This study contributes to pushing the frontiers of plasmonic research from geometric control toward nanostructure engineering and sheds light on new strategies for diverse plasmonic-enhanced applications.