LAUSR

Nanoplasmonics is currently experiencing an ongoing renaissance as a result of the booming research interest in LSPR-mediated but semiconductor-free photocatalysis and photoelectrochemistry directly over nanometals with excellent catalytic activity and conductive properties. To shed light on the underlying mechanism, the present study puts forward H 2 O 2 as the probe molecule, with which the electroreduction at the phase boundary with photoexcited Ag nanowires (NWs) was systemically investigated. In particular, the reaction rate depends not only linearly on the illumination intensity but also on the resonant wavelength of the characteristic LSPR of the Ag NWs, evidently illustrating that the photoelectrochemical H 2 O 2 reduction is mediated by the LSPR-induced energetic electrons of the Ag NWs. In addition to the mechanistic insights, the present study further highlights the great promise of such semiconductor-free LSPR-mediated photoelectrochemistry of H 2 O 2 over Ag NWs in the analytical biochemistry field via proof-of-concept solar photoelectrochemical detection of ultradiluted H 2 O 2 in PBS. The Ag NWs deposited on a carbon cloth substrate as the working electrode exhibit excellent sensitivity amounting to 118 μA cm −2  mM −1 under solar illumination, well outperforming that of the electrochemical counterpart measured in the dark by 50%. A device that employs sunlight and oscillating electrons to identify targets in dilute solutions may be useful in analytical biochemistry. Recent studies have shown that electron oscillations, or plasmons, located on the surface of metal nanoparticles can help speed up chemical reactions by transferring charge to reactants. Yu-Kuei Hsu from National Dong Hwa University in Hualien, Taiwan, and colleagues now demonstrate that solar-driven surface plasmon effects can be used for chemical detection in liquids. The team’s approach uses electrodes composed of silver nanowires deposited on carbon films to measure concentrations of hydrogen peroxide, a molecule involved in many biological processes. Exposing this electrode to solar radiation generates energetic “hot” electrons that travel throughout the liquid and interact with the peroxide. The resulting chemical reaction enhances peroxide detection sensitivity by 50 percent compared to conventional sensors. Mechanistic insights into the LSPR-mediated yet semiconductor-free photoelectrochemistry of H 2 O 2 over Ag NWs under sunlight illumination.