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The development of efficient and yet economic photocatalysts that can utilize solar light is crucial for the sustainable future. We report a simple approach to introduce a bidentate type of metal coordination site in polymeric carbon nitride (PCN) by an in situ keto−enol cyclization route of acetylacetone and urea to incorporate a metal chelating pyrimidine derivative into the molecular framework of PCN. The resulting new metal coordination sites provide both N-and O-complexing ligands unlike the unmodified PCN that has Nligands only. As a proof-of-concept experiment, we introduced Al 3+ ions into these coordination sites, which induced significant enhancements in visible light photocatalytic activities for organic pollutant degradation and H 2 evolution as compared to those of bulk PCN and the conventional "nitrogen pot" metalcoordinated PCN. The optimized Al loading was as low as 0.32 wt %. The photocatalytic activities sensitively depended on the Al incorporation, and the Al-incorporated sample demonstrated an excellent stability in water with showing little sign of metal leaching. While the aluminum ions complexed in the nitrogen pot little influenced the photocatalytic activity, Al 3+ ions complexed by both N and O ligands in the alternative coordination sites significantly enhanced the photocatalytic activity of PCN. This study demonstrates a facile and scalable synthesis of PCN with alternative metal coordination sites for efficient solar energy conversion.

The incorporation of plasmonic properties recently emerged as an advanced strategy for achieving high-performance catalysis. The hot carriers and near-field enhancement induced by localized surface plasmon resonance (LSPR) excitation are the key parameters that are responsible for the enhanced performance. Thus, the logical combination of the plasmonic nanostructures and electrocatalytic materials can be an effective strategy for further widening application of the plasmonic effect. This short Review provides a concise overview of the fundamental principles of LSPR; the mechanism of plasmonenhanced electrocatalysis; alternative design methods of plasmonic nanomaterials for various catalytic systems; and recent progress in plasmon-mediated electrocatalysis for the production of energy, including electrochemical conversion of different feedstocks into fuels along with fuel cell catalysis. This Review also sheds light on the areas where major advancements are required to further improve the field of plasmon-mediated electrocatalysis to achieve a major paradigm shift toward a sustainable future.

In recent years, a promising role of plasmonic metal nanoparticles (NPs) has been demonstrated toward an improvement of the catalytic efficiency of well‐designed hybrid electrocatalysts. In particular, the coupling of plasmonic functionality with the metal‐based core–shell architectures in plasmon‐enhanced electrocatalysis provides a sustainable route to improve the catalytic performances of the catalysts. Herein, the rationally designed AuNPs wrapped with reduced graphene oxide (rGO) spacer along with PdNPs (AuNP@rGO@Pd) as the final composite are reported. The rGO is proposed to promote the reduction of PdO, greatly enhance the conductivity, and catalytic activity of these nanohybrid structures. The plasmon‐enhanced electrocatalytic performance of optimized AuNP@rGO(1)@Pd exhibits an ≈1.9‐ and 1.1‐fold enhanced activity for the hydrogen evolution reaction and oxygen evolution reaction, respectively. The final composite also exhibits a superior stability up to 10000 s compared with the commercial Pd/C. The mechanism of the enhanced catalytic performance is monitored through in situ X‐ray absorption spectroscopy by observing the generated electron density under light irradiation. The results demonstrate that the energetic charge carriers are concentrated in the incorporated PdNPs, allowing higher catalytic performances for the overall water‐splitting reaction. The conclusions herein drawn are expected to shed light on upcoming plasmon‐induced electrocatalytic studies with analogous hybrid nanoarchitectures.

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Extraordinary light–matter interaction on the surface of metallic nanostructures can excite surface plasmons (SPs), followed by generation of charge carriers with high energy, that is, “hot electrons and holes”, via nonradiative decay. Such plasmonic hot carriers are potentially useful for photocatalysis, electrocatalysis, photovoltaics, optoelectronics, and theragnosis since hot carrier transfer to the desired substrate can accelerate specific redox reactions or facilitate electrical benefits on devices. In this regard, there is a growing interest in the detection and visualization of hot carriers at the location where plasmonic hot carriers are practically generated and transferred by means of conventional or newly developed procedures, as summarized in Table 1 of the main paper. Although direct imaging of plasmonic hot carriers or pathways are still challenging due to ultrafast dynamics of plasmonic hot carriers, state-of-the-art microscopic approaches have successfully demonstrated the mapping of the localized surface plasmons (LSPs) and plasmonic hot carriers. In addition, more accessible and facile approaches by mediation of chemical probes have also been emerged in recent years for the same purpose. The aim of this Perspective is to provide an idea of how spatial information on the generation and transfer of plasmonic hot carriers can be associated with the future design of plasmonic nanomaterials or nanocomposites to increase the output of hot carrier-driven processes. Along with a comprehensive overview of surface plasmon decay into plasmonic hot carriers and the necessity of plasmonic hot carrier imaging, we will highlight some recent advances in plasmonic hot carrier imaging techniques and provide remarks on future prospects of these techniques.

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