Abstract

Understanding charge transfer at semiconductor–metal interfaces is central to advancing photoelectronic materials, yet real-time monitoring of such ultrafast processes remains elusive. Here, we introduce a hybrid nanoarray-enhanced laser desorption/ionization mass spectrometry (HyNA-LDI-MS) strategy that enables direct and rapid tracking of photoelectrons and hot carriers at hybrid interfaces. Using juglone as an electron scavenger and representative analytes as hole probes, we provide mass spectrometric evidence of interfacial charge generation and reveal markedly higher transfer efficiency at conductive interfaces compared with insulating ones. Incorporating 4-methylbenzylpyridinium as a chemical thermometer uncovers a competition between charge transfer and photothermal heating: conductive interfaces favor efficient electron transfer that suppresses heat generation, while insulating ones convert excited electrons predominantly into thermal energy. These insights, supported by complementary optoelectronic studies and density functional theory-calculations, establish HyNA-LDI-MS as a powerful tool to unravel charge-energy dynamics at complex interfaces. This study provides fundamental insights into interfacial processes, guiding the design of high-performance analytical platforms such as LDI-MS systems and offering significant implications for related biomedical applications.

Scheme 1 Overall schematic of the hybrid nanoarray enhanced laser desorption ionization mass spectrometry (HyNA-LDI-MS) approach for probing interfacial charge transfer.

Fig. 1 Fabrication andcharacterization of TiO2/Au hybrid nanoarrays (HyNAs). (a) Illustration of the construction process for TiO2/Au HyNAs with conductive andinsulating heterointerfaces. SEMimageof conductivenanoarrays(Con-NAs)isshownontheright.(b)Zetapotentialofnegatively charged Au NPs(Au(−)), Au@ b-CDNPs, andTiO2@DANPs. (c)TheUV-visabsorptionspectra of Au(−), Au@ b-CD NPs, TiO2@DANPs,Con-NAs and In-NAs. (d) The FT-IR spectra of Con-NAs and In-NAs. (e) Photocurrent analysis of Au NPs, TiO2 NPs, Con-NAs, and In-NAs. (f) PL spectrum of TiO2@DA, Au(−), Con-NAs, and In-NAs. (g) Mott–Schottky plots of Con-NAs and In-NAs, recorded for electrodes measured in 0.2 M K2SO4 solution at 10 kHz. (h) XPS spectra of In-NAs and Con-NAs, including the survey spectrum and high-resolution spectra of Ti 2p (i) and Au 4f (j).

DOI: https://doi.org/10.1039/D6TA00438E