Realization of Al:ZnO (AZO)-Ag nanocomposite as a novel photocatalyst capable of broadband photon harnessing driven by near-infrared plasmonics

Abstract

The rising level of environmental pollution is a global concern and towards its mitigation, infrared photocatalysis emerges as a new concept, as the solar radiation at the earth’s surface has over 50% energy distribution in the near infrared (NIR) region. Al-doped ZnO (AZO) is a non-toxic congener of indium tin oxide (ITO) as transparent conducting oxide (TCO). A TCO-metal framework is developed as AZO-Ag@AZO nanocomposite by pulsed DC/DC magnetron sputtering. The consequences of diverse process conditions, viz, doping level, sputtering pressure, deposition time, and Ag/AZO co-sputtering time are noteworthy as the morphological, compositional, optical, and electrical properties are critically dependent on the process conditions. The structural and compositional analyses confirm wurtzite AZO and f.c.c. Ag with nanosized crystalline domains. A series of photocatalysis experiments reveal the significance of NIR plasmonics of AZO, realized by nanostructuring and generating optimum electron density (∼1020 cm−3). Notably, the optimal degradation rate (95%) of R6G is attained with tailored AZO-Ag@AZO nanocomposite. The gravity of visible surface plasmon resonance (SPR) due to Ag nanocrystallites and electron-hole pair creation in AZO cannot be undermined due to the remarkable participation of energetic electrons, and holes in redox reactions in harmony with actions of NIR SPR driven lower energy electrons.