Promising Electrochemiluminescence from CuInS₂/ZnS Nanocrystals/Hydrazine via Internal Cu(I)/Cu(II) Couple Cycling

Abstract

Screening a novel electrochemiluminescence (ECL) system is crucial to ECL evolution. Herein, an efficient ECL system with less interference and environmental concern under physiological condition is developed via a unique internal Cu­(I)/Cu­(II) couple cycling amplified strategy by employing the glutathione- and citrate-capped copper indium sulfide (CIS)/ZnS nanocrystals (NCs) as electro­chemiluminophore and N2H4·H2O as co-reactant. CIS/ZnS NCs can be electrochemically injected with valence band (VB) hole at 0.46 and 0.87 V (vs Ag/AgCl), and then achieve the same hole-injected states by relocalizing VB holes with the Cu­(I) species inside of CIS/ZnS NCs to form internal Cu­(II) defects, while each N2H4·H2O molecule can be successively oxidized to two more reducing species N2H3 • and N2H2 around 0.10 V, and inject conduction band (CB) electron onto CIS/ZnS NCs for triple times. The internal Cu­(I)/Cu­(II) couple cycling involved radiative-charge recombination between these VB hole and CB electron eventually enables two efficient near-infrared ECL processes (around 731 nm) at 0.55 and 0.87 V, in which each single nanocrystal may participate in multiple ECL reaction cycles to produce multiple photons for amplified ECL, similar to the tris­(bipyridyl)­ruthenium­(III) based ECL system. The low-triggering-potential ECL process at 0.55 V can be utilized to selectively determine Cu­(II) with a wide linear range from 10 and 1500 nM and a limit of detection of 5 nM (S/N = 3). This work presents a NCs engineering and co-reactant selecting combined strategy for further ECL evolution.

Surface-Defect-Induced and Synergetic-Effect-Enhanced NIR-II Electrochemiluminescence of Au–Ag Bimetallic Nanoclusters and Its Spectral Sensing

“…The EDS spectrum of Au–Ag BNCs displayed strong characteristic peaks of Ag, Au, and S (Figure B), and the surface element ratio of Au/Ag was determined to be 5:3 (inset of Figure B), which was approximately consistent with the precursor Au/Ag molar ratio of 2:1. The XRD pattern exhibited four peaks with 2θ values of 38.1, 41.8, 64.5, and 79.6°, which were consistent with those of the face-centered cubic (fcc) Ag (JCPDS 04-0783) and Au (JCPDS 04-0784) (Figure C). ,, XPS spectra provided further evidence that Au–Ag BNCs did contain Au, Ag, and S elements (Figure D). The Ag-3d pattern exhibited two strong peaks for Ag-3d 5/2 (368 eV) and Ag-3d 3/2 (374 eV) (inset b of Figure D), which match well with those of zero-valent Ag .…”

“…Some Met-capped Au–Ag BNCs exhibited both band gap-engineered PL and defect-induced PL together, while the other Met-capped Au–Ag BNCs, which were prepared with a precursor Au/Ag molar ratio of less than 3:1, failed to exhibit the band gap-engineered PL. Both the precursor Au/Ag molar ratio and pH of the precursor mixture A exhibited significant effects on PL of Met-capped Au–Ag BNCs (Figure S1A,C), indicating that synthesis conditions could alter the radiative charge-combination processes of Au–Ag BNCs . The precursor Au/Ag molar ratio of 2:1 and the pH of precursor mixture A of 12.0 were utilized as typical synthesis conditions in this case.…”

“…Both the precursor Au/Ag molar ratio and pH of the precursor mixture A exhibited significant effects on PL of Met-capped Au−Ag BNCs (Figure S1A,C), indicating that synthesis conditions could alter the radiative charge-combination processes of Au− Ag BNCs. 41 The precursor Au/Ag molar ratio of 2:1 and the pH of precursor mixture A of 12.0 were utilized as typical synthesis conditions in this case. The efficient monochromatic PL around 756 nm from Met-capped Au−Ag BNCs was primarily generated in a defect-related way (Figure 1A).…”

Hydrazine Hydrate and Dissolved Oxygen-Triggered Near-Infrared Chemiluminescence from CuInS2@ZnS Nanocrystals for Bioassays

“…Subsequently, N 2 H 3 • reacted with O 2 to form O 2 •– , which injected holes into the valence band of CIS@ZnS NCs. Then, the electrons and holes recombined and emitted light through the Cu + defects in CIS@ZnS NCs, similar to the charge-transfer route for ECL of the CIS@ZnS NCs/N 2 H 4 ·H 2 O system . Meanwhile, the surface ligand LA was simultaneously oxidized.…”

Progress in spectrum-based electrochemiluminescence quantitative analysis

“…Long等 [97] . Fu等以水合肼为共反应剂 实现了CIS/ZnS量子点在0.55 V附近的ECL辐射 [98] , 有 效降低了CIS/ZnS量子点ECL发光电位和电化学干扰; 以碳酰肼为共反应剂进一步实现了多种ECL物质在 0.55 V附近的低电位ECL辐射 [99] , 为低电位单波段 ECL体系的研发提供了新思路.…”