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Single atom (SA), noble metal catalysts are of interest due to high projected catalytic activity while minimizing cost. Common issues facing many synthesis methodologies include complicated processes, low yields of SA product, and production of mixtures of SA and nanoparticles (NPs). Herein we report a simple, room-temperature synthesis of single Pt-atom decorated, anatase Fe-doped TiO2particles that leverages the Fe dopant as an engineered defect site to photodeposit and stabilize atomically dispersed Pt. Both particle morphology and Fe dopant location are based on thermodynamic principles (Gibbs–Wulff construction). CO–DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) reveals absence of bridge-bonded CO signal, confirming atomically dispersed Pt. XAS (X-ray absorption spectroscopy) of both Pt and Fe indicates Fe–O–Pt bonding that persists through catalytic cycling. Mass balance indicates that the Pt loading on single particles is 2.5 wt % Pt; the single Pt-atom decorated nanoparticle yield is 17%. Pt-containing particles show more than an order-of-magnitude increased photooxidation efficiency relative to particles containing only Fe. High single-atom-Pt yield, ease of synthesis, and high catalytic activity demonstrate the utility and promise of this method. The principles of this photodeposition synthesis allow for its generalizability toward other SA metals of catalytic interest.

Atomically dispersed Pd/ZnO was synthesized using a facile method. We found that 0.07 wt % Pd was isolated and positively charged on ZnO synthesized using a solvothermal method. By contrast, Pd clusters were formed on commercial ZnO, with the difference between the two supports residing in their different number of defects and surface area. Pd atoms are selective in the ethanol dehydrogenation reaction to form acetaldehyde and H2exclusively, while Pd clusters decompose ethanol to form CO and CH4as byproducts. Our work proves that the structure of Pd affects the selectivity of the reaction, and isolated Pd sites, unlike the contiguous Pd metal sites, catalyze the selective C–H bond scission while keeping the C–C bond intact. Pd atoms also showed higher stability in the reaction, since they did not suffer from coke formation. This work provides new insights to enable the design of selective and stable Pd-based catalysts for alcohol conversion reactions.

Elucidation of reaction mechanisms and the geometric and electronic structure of the active sites themselves is a challenging, yet essential task in the design of new heterogeneous catalysts. Such investigations are best implemented via a multipronged approach that comprises ambient pressure catalysis, surface science, and theory. Herein, we employ this strategy to understand the workings of NiAu single-atom alloy (SAA) catalysts for the selective nonoxidative dehydrogenation of ethanol to acetaldehyde and hydrogen. The atomic dispersion of Ni is paramount for selective ethanol to acetaldehyde conversion, and we show that even the presence of small Ni ensembles in the Au surface results in the formation of undesirable byproducts via C–C scission. Spectroscopic, kinetic, and theoretical investigations of the reaction mechanism reveal that both C–H and O–H bond cleavage steps are kinetically relevant and single Ni atoms are confirmed as the active sites. X-ray absorption spectroscopy studies allow us to follow the charge of the Ni atoms in the Au host before, under, and after a reaction cycle. Specifically, in the pristine state the Ni atoms carry a partial positive charge that increases upon coordination to the electronegative oxygen in ethanol and decreases upon desorption. This type of oxidation state cycling during reaction is similar to the behavior of single-site homogeneous catalysts. Given the unique electronic structure of many single-site catalysts, such a combined approach in which the atomic-scale catalyst structure and charge state of the single atom dopant can be monitored as a function of its reactive environment is a key step toward developing structure–function relationships that inform the design of new catalysts.