Epitaxial growth is one of the most commonly used strategies to precisely tailor heterostructures with well-defined compositions, morphologies, crystal phases, and interfaces for various applications. However, as epitaxial growth requires a small interfacial lattice mismatch between the components, it remains a challenge for the epitaxial synthesis of heterostructures constructed by materials with large lattice mismatch and/or different chemical bonding, especially the noble metal-semiconductor heterostructures. Here, we develop a noble metal-seeded epitaxial growth strategy to prepare highly symmetrical noble metal-semiconductor branched heterostructures with desired spatial configurations, i.e., twenty CdS (or CdSe) nanorods epitaxially grown on twenty exposed (111) facets of Ag icosahedral nanocrystal, albeit a large lattice mismatch (more than 40%). Importantly, a high quantum yield (QY) of plasmon-induced hot-electron transferred from Ag to CdS was observed in epitaxial Ag-CdS icosapods (18.1%). This work demonstrates that epitaxial growth can be achieved in heterostructures composed of materials with large lattice mismatches. The constructed epitaxial noble metal-semiconductor interfaces could be an ideal platform for investigating the role of interfaces in various physicochemical processes.

Heterogenization of homogenous catalysts on electrode surfaces provides a valuable approach for characterization of catalytic processes in operando conditions using surface selective spectroelectrochemistry methods. Ligand design plays a central role in the attachment mode and the resulting functionality of the heterogenized catalyst as determined by the orientation of the catalyst relative to the surface and the nature of specific interactions that modulate the redox properties under the heterogeneous electrode conditions. Here, we introduce new [Re(L)(CO) 3 Cl] catalysts for CO 2 reduction with sulfur-based anchoring groups on a bipyridyl ligand, where L = 3,3 ′-disulfide-2,2 ′-bipyridine (SSbpy) and 3,3 ′-thio-2,2 ′-bipyridine (Sbpy). Spectroscopic and electrochemical analysis complemented by computational modeling at the density functional theory level identify the complex [Re(SSbpy)(CO) 3 Cl] as a multi-electron acceptor that combines the redox properties of both the rhenium tricarbonyl core and the disulfide functional group on the bipyridyl ligand. The first reduction at −0.85 V (vs. SCE) involves a two-electron process that breaks the disulfide bond, activating it for surface attachment. The heterogenized complex exhibits robust anchoring on gold surfaces, as probed by vibrational sum-frequency generation (SFG) spectroscopy. The binding configuration is normal to the surface, exposing the active site to the CO 2 substrate in solution. The attachment mode is thus particularly suitable for electrocatalytic CO 2 reduction.

A well-known catalyst, fac-Re(4,4′-R 2 -bpy)(CO) 3 Cl (bpy = bipyridine; R = COOH) (ReC0A), has been widely studied for CO 2 reduction; however, its photocatalytic performance is limited due to its narrow absorption range. Quantum dots (QDs) are efficient light harvesters that offer several advantages, including size tunability and broad absorption in the solar spectrum. Therefore, photoinduced CO 2 reduction over a broad range of the solar spectrum could be enabled by ReC0A catalysts heterogenized on QDs. Here, we investigate interfacial electron transfer from Cd 3 P 2 QDs to ReC0A complexes covalently bound on the QD surface, induced by photoexcitation of the QD. We explore the effect of triethylamine, a sacrificial hole scavenger incorporated to replenish the QD with electrons. Through combined transient absorption spectroscopic and computational studies, we demonstrate that electron transfer from Cd 3 P 2 to ReC0A can be enhanced by a factor of ∼4 upon addition of triethylamine. We hypothesize that the rate enhancement is a result of triethylamine possibly altering the energetics of the Cd 3 P 2 −ReC0A system by interacting with the quantum dot surface, deprotonation of the quantum dot, and preferential solvation, resulting in a shift of the conduction band edge to more negative potentials. We also observe the rate enhancement in other QD−electron acceptor systems. Our findings provide mechanistic insights into hole scavenger−quantum dot interactions and how they may influence photoinduced interfacial electron transfer processes.

Covalent attachment of molecular catalysts to electrode surfaces is an attractive approach to develop robust catalytic materials. Selectivity and tunability of the resulting catalytic surface can be achieved by ligand design, making surfaceattached CO 2 catalysts of immense interest for zero carbon technologies. Unfortunately, the functionality of heterogenized catalysts strongly depends on the nature of the electrode surface and the specific binding mode of the catalyst on the electrode surface. Here, we perform experimental and theoretical vibrational sum-frequency generation spectroscopy (VSFG) to investigate the binding configuration of a popular molecular CO 2 reduction catalyst, the Re(dcbpy)(CO) 3 Cl (dcbpy = 4,4′-dicarboxy-2,2′bipyridine) complex (ReC0A), heterogenized on a 0.5% niobium (Nb)-doped rutile TiO 2 (100) crystal. We find evidence of ligand exchange induced upon binding to the (100) TiO 2 facet that was not observed on other TiO 2 facets. The structural changes are induced by the sawtooth morphology of the TiO 2 (100) facet, establishing interactions that lead to chloride (Cl − ) ligand exchange with hydroxide (OH − ) and formation of the Re(dcbpy)(CO) 3 OH (ReOH) adsorbate. DFT calculations show bidentate binding of ReOH through its carboxylate (COO − ) groups in a flat-lying orientation stabilized by hydrogen-bonding of the OH − proton to the TiO 2 surface. The OH-substituted site interacts strongly with the (100) TiO 2 surface in a configuration unfavorable for the CO 2 exchange that is necessary for catalytic functionality. These findings provide evidence of facet-dependent changes of the heterogenized molecular catalyst, underscoring the critical role of the surface facet while designing electrocatalytic materials.