Correlative <i>in situ</i> x-ray photoelectron spectroscopy and transmission electron microscopy characterization under identical reaction conditions

Acquiring information on the evolution of chemical states and real-space morphological changes under identical reaction conditions is crucial for elucidating the mechanisms of heterogeneous catalytic reactions. In this study, we design and implement a microreactor with high electron transparency, enabling correlated in situ x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements for the same type of sample under identical reaction environments, while integrating online mass spectrometry for seamless coupling of spectroscopic and imaging data. This advancement allows direct correlation between the in situ chemical-state information obtained by XPS and the real-space structural evolution captured by TEM. Using the oxidation-reduction process of Ni nanoparticles in O2/H2 atmospheres as a model reaction, we systematically investigate the dynamic relationship between surface chemical states and morphological reconstruction from near-ambient to ambient pressures, demonstrating the stability and applicability of the microreactor under complex gas environments. This work provides a new experimental approach for mechanistic studies of gas-solid interfacial reactions under realistic operating conditions and establishes a methodological foundation for the rational design and optimization of high-performance catalysts.