Physical Origin of Dual-Emission of Au-Ag Bimetallic Nanoclusters

Bo Peng; Liu-Xi Zheng; Pan-Yue Wang; Jia-Feng Zhou; Meng Ding; Hao-Di Sun; Bing-Qian Shan; Kun Zhang

doi:10.3389/fchem.2021.756993

Physical Origin of Dual-Emission of Au-Ag Bimetallic Nanoclusters

Front Chem. 2021 Sep 27:9:756993. doi: 10.3389/fchem.2021.756993. eCollection 2021.

Authors

Bo Peng¹, Liu-Xi Zheng¹, Pan-Yue Wang¹, Jia-Feng Zhou¹, Meng Ding¹, Hao-Di Sun¹, Bing-Qian Shan¹, Kun Zhang^{1

2

3}

Affiliations

¹ Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai, China.
² Laboratoire de Chimie, Ecole Normale Supérieure de Lyon, Institut de Chimie de Lyon, Université de Lyon, Lyon, France.
³ Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China.

Abstract

On the origin of photoluminescence of noble metal NCs, there are always hot debates: metal-centered quantum-size confinement effect VS ligand-centered surface state mechanism. Herein, we provided solid evidence that structural water molecules (SWs) confined in the nanocavity formed by surface-protective-ligand packing on the metal NCs are the real luminescent emitters of Au-Ag bimetal NCs. The Ag cation mediated Au-Ag bimetal NCs exhibit the unique pH-dependent dual-emission characteristic with larger Stokes shift up to 200 nm, which could be used as potential ratiometric nanosensors for pH detection. Our results provide a completely new insight on the understanding of the origin of photoluminescence of metal NCs, which elucidates the abnormal PL emission phenomena, including solvent effect, pH-dependent behavior, surface ligand effect, multiple emitter centers, and large-Stoke's shift.

Keywords: Bimetallic nanoclusters; Dual-emission; Structural water molecules; nanoscale interface; pH ratiometric sensing.