Colloquium

Friday 10 December 2021

Speaker

Gerasimos Armatas

Affiliation

Dept. of Materials Science and Technology, University of Crete

Title

Assembling Mesoscopic Nano-heterostructures with Improved Interfaces for Solar Photocatalytic Applications

Location

Room A2 (A115-A117) of CSD Building (ground floor, north wing) and online. Please visit the link.

Time

11:00

Language

English

Abstract

Semiconductor photocatalysis has recently emerged as an effective and eco-friendly approach that could meet the stringent requirements for sustainable clean energy conversion and environmental remediation. To this end, the fabrication of novel photocatalysts with unique electrochemical properties, high catalytic efficiency and long-term stability is of utmost importance and requires adequate attention. Recently, the synthesis of nanostructured mesoporous metal chalcogenides has been the focus in the field of photo- and electro-catalysis. These materials combine the high electron mobility, excellent visible-light response and unique photochemical properties of metal chalcogenide nanocrystals (NCs) with mesoporosity, offering new perspectives in devising novel photocatalysts with improved efficiency and reliability.

In this presentation we will demonstrate that 3D mesoporous architectures, comprising well-defined interconnected metal sulfide NCs, can be prepared through a polymer-templated self-assembly of colloidal nanoparticles. The resulting ensemble structures that obtained after template removal impart the unique combination of photocatalytic reactivity of inorganic NCs and 3D open-pore structure, high surface area and uniform pores of a mesoporous material. We will show that the pore surface of CdS and ZnS linked NCs is active and accessible to incoming molecules, exhibiting high photocatalytic performance and stability in the water splitting reaction towards the generation of H2 as a solar fuel. These results mark an interesting strategy for enhancing interface charge transfer properties and hydrogen evolution activity of metal sulfides by engineering interfaces at the nanoscale. Moreover, through appropriate selection of the synthetic methods, we will present the synthesis of 2D/2D layer nano-heterostructures composed of exfoliated Ni-doped MoS₂ nanosheets and g-C₃N₄ layers. These layered heterostructures, which exhibit reduced interfacial resistance, high carrier density and improved charge transfer kinetics at the catalyst interface, can carry out photocatalytic reduction of toxic Cr(VI) to less harmful Cr(III) and oxidation of water to dioxygen under visible light with outstanding activity. The results of this work mark an important step forward in understanding and designing low-cost and high-efficiency catalysts for environmental remediation applications, including detoxification of Cr(VI) polluted industrial effluents.