Engineering Noble Metals Single-Atom Catalysts for Photothermal-Enhanced Photocatalytic Hydrogen Production.

Photothermal-enhanced photocatalytic hydrogen evolution (PHE) converts nonradiative losses into localized interfacial heating, while precious-metal single-atom catalysts (SACs) offer atom-efficient and well-defined active sites. However, progress remains difficult to compare and translate because reaction-zone temperatures are often poorly constrained, the active forms of single atoms under light and heat are rarely verified, and performance in model suspensions does not readily extend to practical reactors or long-term operation. This Review summarizes major material platforms for photothermal harvesting and single-atom site design, and defines key support requirements, including strong light absorption, efficient charge and heat transport, and stable anchoring sites. It also outlines the typical roles of different noble metals and proposes actionable frameworks for the field. Thermometry-anchored protocols help disentangle thermal, photochemical, and synergistic effects through temperature-matched controls, absorption-normalized kinetics, and activation-energy benchmarks. An operando and ultrafast evidence framework tracks coordination, valence, charge transfer, and intermediates in real time, enabling verification of dynamic active sites. Finally, scale-relevant design rules connect photon and heat management with mass transport, bubble dynamics, scalable synthesis, and long-term validation, guiding photocatalysis toward mechanistically accountable and deployable solar H