  Multi-electron transfer processes, such as hydrogen and oxygen evolution
reactions, are crucially important in energy and biological science but require
favorable catalysts to achieve fast kinetics. Nanostructuring catalysts can
dramatically improve their properties, which can be difficult to understand due
to strain and size dependent thermodynamics, the influence of defects, and
substrate dependent activities. Here, we report 3D imaging of single gold
nanoparticles during catalysis of ascorbic acid decomposition using Bragg
coherent diffractive imaging (BCDI) as a route to eliminate ensemble effects
while elucidating the strain-activity connection. Local strains were measured
in single nanoparticles and modeled using reactive molecular dynamics (RMD)
simulations and finite element analysis (FEA) simulations. RMD reveals a new
chemical pathway for local strain generation in the gold lattice: chemisorption
of hydroxyl ions. FEA reveals that the RMD results are transferable to the
larger nanocrystal sizes studied in the experiment. Our study reveals the
strain-activity connection and opens a powerful new avenue for joint
theoretical and experimental studies of multi-electron transfer processes
catalyzed by nanocrystals.
