Harvesting Lost Photons: Plasmon and Upconversion Enhanced Broadband Photocatalytic Activity in Core@Shell Microspheres Based on Lanthanide‐Doped NaYF<sub>4</sub>, TiO<sub>2</sub>, and AuZhenhe Xu, Dongling Ma, Mohamed Chaker et al.|Advanced Functional Materials|2015Cited by 297