Amorphous NiFe Oxide-based Nanoreactors for Efficient Electrocatalytic Water Oxidation

Synergy engineering is an important way to enhance the kinetic activity of oxygen-evolution-reaction (OER) electrocatalysts. Here, we fabricated NiFe amorphous nanoreactor (NiFe-ANR) oxide as OER electrocatalysts via a mild self-catalytic reaction. Firstly, the amorphousness helps transform NiFe-ANR into highly active hydroxyhydroxides, and its many fine-grain boundaries increase active sites. More importantly, as proved by experiments and finite element analysis, the nanoreactor structure alters the spatial curvature and the mass transfer over the catalyst, thereby enriching OH^- in the catalyst surface and inner part. Thus, the catalyst with the structure of amorphous nanoreactors gained excellent activity, far superior to the NiFe catalyst with the structure of crystalline nanoreactor or amorphous non-nanoreactor. This work provides new insights into the applications and mechanisms of amorphousness and nanoreactors, embodying the "1+1>2" synergy of crystalline state and morphology.

Single-entity Electrochemistry Unveils Dynamic Transformation during Tandem Catalysis of Cu2 O and Co3 O4 for Converting NO3 - to NH3

Electrochemically converting nitrate to ammonia is an essential and sustainable approach to restoring the globally perturbed nitrogen cycle. The rational design of catalysts for the nitrate reduction reaction (NO₃ RR) based on a detailed understanding of the reaction mechanism is of high significance. We report a Cu₂ O+Co₃ O₄ tandem catalyst which enhances the NH₃ production rate by ≈2.7-fold compared to Co₃ O₄ and ≈7.5-fold compared with Cu₂ O, respectively, however, most importantly, we precisely place single Cu₂ O and Co₃ O₄ cube-shaped nanoparticles individually and together on carbon nanoelectrodes provide insight into the mechanism of the tandem catalysis. The structural and phase evolution of the individual Cu₂ O+Co₃ O₄ nanocubes during NO₃ RR is unveiled using identical location transmission electron microscopy. Combining single-entity electrochemistry with precise nano-placement sheds light on the dynamic transformation of single catalyst particles during tandem catalysis in a direct way.

Enhanced Electrochemistry of Single Plasmonic Nanoparticles

The structure-function relationship of plasmon enhanced electrochemistry (PEEC) is of great importance for the design of efficient PEEC catalyst, but is rarely investigated at single nanoparticle level for the lack of efficient nanoscale methodology. Herein, we report the utilization of nanoparticle impact electrochemistry to allow single nanoparticle PEEC, where the effect of incident light on the plasmonic Ag/Au nanoparticles for accelerating Co-MOFNs catalyzed hydrogen evolution reaction (HER) is systematically explored. It is found that the plasmon excited hot carrier injection can lower the reaction activation energy, resulting in a much promoted reaction probability and the integral charge generated from individual collisions. Besides, a plasmonic nanoparticle filtering method is established to effectively distinguish different plasmonic nanoparticles. This work provides a unique view in understanding the intrinsic physicochemical properties for PEEC at the nano-confined domains.