Understanding the interaction of metal with metal oxides is essential for establishing the structure–activity relationship in heterogeneous catalysis. Herein, a series of nickel–iron-based bimetallic catalysts are systematically investigated to unveil the nature of active sites for the CO2 hydrogenation reaction. An environmental-sensitive strong metal–support interaction between Ni nanoparticles and iron oxides is revealed by a series of characterizations, including HR-TEM, H2-TPR, quasi in situ XPS, and time-resolved in situ DRIFTS. Iron oxides migrate and entirely cover the metallic Ni nanoparticles during the reaction, yielding a more active core–shell-type structure with much-improved reducibility. Such a reconstruction process is also indirectly monitored in a time-resolved manner by in situ DRIFTS and confirmed to complete within 30 min of the reaction.

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Chemiluminescence (CL) probes that possess near-infrared (NIR) emission are highly desirable for in vivo imaging due to their deeper tissue penetration ability and intrinsically high sensitivity. Herein, a novel iridium-based CL probe (NIRIr-CL-1) with direct NIR emission was reported as the result of hypochlorous acid (HClO)-initiated oxidative deoximation. To improve its biocompatibility and extend the CL time for in vivo imaging applications, this NIRIr-CL-1 was prepared as a CL nanoparticle probe (NIRIr-CL-1 dots) through encapsulation by an amphiphilic polymer Pluronic F127 (F127). All results demonstrate that the NIRIr-CL-1 dots have good selectivity and sensitivity for visualization of HClO even at the depth of 1.2 cm. Owing to these advantages, the CL imaging of exogenous and endogenous HClO in mice was achieved. This study could provide new insights into the construction of new NIR emission CL probes and expand their applications in biomedical imaging.