In a groundbreaking advance that challenges long-held views in heterogeneous catalysis, researchers from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences have captured direct microscopic images of a process called bulk oxygen spillover in ruthenium-supported rutile titanium dioxide catalysts. This pioneer work, published in Nature on April 15, 2026, provides the first-ever visual evidence that oxygen species migrate not only along catalyst surfaces but also through the interior bulk at the atomic scale, fundamentally redefining how catalytic reactions may be engineered in solid catalysts.
Traditional wisdom holds that spillover—the migration of atomic or molecular species such as hydrogen or oxygen from an active metal site onto and across a catalyst support—occurs predominantly at surfaces, where reactants are accessible. This transfer is critical for tuning catalytic activity and selectivity. Yet despite the recognized importance of spillover, the microscopic pathways by which oxygen travels, and whether it infiltrates the catalyst bulk to participate in reactions, have remained elusive due to technological limitations.
Employing cutting-edge environmental transmission electron microscopy (ETEM), the research team overcame these barriers to observe oxygen’s journey at the metal-support interface with unprecedented atomic resolution. Using TiO2 as the reducible oxide support and ruthenium nanoparticles as the active metal phase, they demonstrated that oxygen species migrate from beneath the oxide surface—specifically three to five atomic layers deep—across the interface into the Ru metal catalyst. This discovery reveals a hitherto hidden oxygen transport channel within the bulk material, screened by an atomic-scale “guard” at the interface that controls oxygen permeability.
Titanium dioxide, chosen for its reducibility and versatile crystal structures, proved to be an ideal platform for this investigation. Its ability to store and release oxygen within its lattice enables a dynamic reservoir facilitating the spillover process. This reducible nature combined with the unique interface with ruthenium provided a fertile environment to probe how bulk oxygen migration contributes to catalytic function in ways previously considered inaccessible or irrelevant.
The implications of this finding are profound. For nearly five decades, the metal-support interaction phenomenon has predominantly focused on effects localized at the catalyst exterior, such as adsorbate binding on metal surfaces partially encapsulated by oxide supports. This new research broadens the scope by highlighting that interior interfaces within the catalyst bulk play an active role in mass transport, essentially unlocking a new dimension in catalytic design. This “inside-out” perspective could transform strategies for creating highly efficient catalysts by deliberately engineering interface structures that optimize bulk spillover behavior.
A crucial feature identified by the researchers is the atomic-scale interface acting as a selective gatekeeper. This interface determines whether oxygen species are permitted to pass from the TiO2 lattice to the Ru metal. Such findings elevate interface engineering as a powerful tool to modulate spillover dynamics, potentially controlling reaction pathways and improving catalyst stability and turnover frequency by harnessing the entire three-dimensional architecture of the catalyst rather than relying solely on surface phenomena.
Moreover, this bulk spillover mechanism driven by oxygen chemical potential changes the fundamental understanding of mass transfer in catalytic conversions. It suggests that catalysts thought to be “inactive” in their interior volumes can be reimagined to utilize those regions effectively, leveraging oxygen transport channels that connect subsurface oxide layers to metal phases embedded within. This fresh insight offers an unexplored avenue to enhance catalytic performance beyond conventional surface-limited reactions.
The breakthrough also exemplifies the power of in situ microscopic techniques. By directly imaging single catalyst particles under reactive environmental conditions, the team elucidated real-time atomic-scale mechanisms that traditional ensemble-averaged spectroscopies could not resolve. Such advanced imaging stands to become an indispensable approach for decoding the complex atomic choreography in catalysis, enabling rational design of next-generation catalytic materials with precision tuning of bulk and interfacial processes.
Looking forward, the team envisions expanding this foundational work to develop catalysts engineered for full “surface-interface-bulk” synergy. This paradigm shifts from viewing catalyst surfaces as the sole reactive sites toward embracing three-dimensional architectures where interface and bulk phenomena collaborate to drive chemical transformations efficiently. Such integrated catalytic architectures might unlock new chemistries or allow better control of existing reactions relevant to energy, environment, and chemical synthesis sectors.
Prof. Zhang Tao, leading the effort, highlighted the transformative potential of this approach, noting that their discoveries provide a new blueprint for atomic-level interfacial engineering in heterogeneous catalysis. The next milestones involve designing practical catalysts exploiting bulk spillover pathways to directly contribute to reaction kinetics and selectivity, pushing catalytic science from two-dimensional to three-dimensional functional control.
The discovery of interface-controlled bulk oxygen spillover not only challenges classical catalysis paradigms but opens a new frontier for fundamental studies and technological innovations. As scientists delve deeper, this breakthrough could spur the invention of catalysts with enhanced efficiency and durability, contributing to sustainable chemical processes critical for future energy and environmental solutions.
Subject of Research: Not applicable
Article Title: Imaging interface-controlled bulk oxygen spillover
News Publication Date: 15-Apr-2026
Web References: 10.1038/s41586-026-10324-x
Image Credits: Dalian Institute of Chemical Physics (DICP)
Keywords
Catalysis, Oxygen Spillover, Metal-Support Interaction, Environmental Transmission Electron Microscopy, Bulk Transport, Ruthenium Catalysts, Titanium Dioxide, Interface Engineering, Heterogeneous Catalysis, Atomic-Scale Imaging, Reducible Oxides, Catalyst Design
Tags: atomic scale oxygen diffusionbulk oxygen spillover in catalysiscatalytic activity and selectivity tuningenvironmental transmission electron microscopy in catalysisheterogeneous catalysis oxygen spilloverinterface-controlled oxygen migrationmetal-support interface oxygen transfermicroscopic imaging of catalyst reactionsoxygen species migration in solid catalystspioneering oxygen spillover visualizationreducible oxide catalyst supportsruthenium-supported TiO2 catalysts
