Water oxidation reaction, widely recognized as the kinetic bottleneck of artificial photosynthesis, limits solar fuel efficiency. It demands the dynamic transfer of multiple electrons and protons at a complex catalyst–liquid interface, where photogenerated holes dynamic accumulate on the catalyst surface, drive atomic-scale structural rearrangements, and regulate chemical bond breaking and formation. Despite its status as a "Holy Grail" reaction for renewable solar fuels, the dynamic spatial coupling of charge transfer, localized structural motifs and active-site evolution remains unresolved in space and time, particularly as identified under operando conditions, obscuring key mechanistic pathways.
Now, a research team led by Prof. LI Can and Prof. FAN Fengtao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. LI Jian-feng's team from Xiamen University, has broken this barrier. In a paper published in Nature Nanotechnology, they integrated operando electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) with nanoscale electrochemical reaction imaging to spatially resolve the atomic-scale interplay between hole transfer dynamics and the evolution of water oxidation intermediates on faceted BiVO4 particles.
The researchers discovered a critical hole density threshold that dictates pathway bifurcation. Below a surface hole density of 0.67 nm-2, both the (110) and (010) facets operate under single-hole-transfer-limited kinetics, stabilizing hydroperoxo (*OOH) and peroxo (*OO) intermediates. In this regime, the (110) facet exhibits slightly higher intrinsic activity. Above this critical threshold, the (010) facet becomes catalytically superior, exhibiting third-order power-law kinetics driven by dynamic multi-hole accumulation within Bi-O-V core structures via peroxo intermediates. The (110) facet, meanwhile, shifts toward accumulating dual oxidizing equivalents, which facilitates intramolecular O–O coupling but demands higher energy input.
These findings shift the current understanding of water oxidation catalysis from a static, site-centric model to a dynamic system governed by mulithole-mediated structural adaptability. Holes, the study shows, are not merely charge carriers-they actively reorganize catalytic centers in response to their own accumulation. This provides a new design principle for artificial photosynthesis: tailoring photocharge–catalyst architectures with atomic-scale precision, rather than focusing solely on static material structures.
"Our operando nanoscale imaging and spectroscopy reveals that water oxidation is not dominated by static active sites, but by a multihole accumulation-driven, self-adaptive mechanism that dynamically reconfigures reaction pathways on different crystal facets," said Prof. FAN. "This shifts catalyst design from optimizing static structures to engineering the dynamic coupling between photogenerated charges and catalyst architecture," said Prof. LI.