Block‐Copolymers Enable Direct Reduction and Structuration of Noble Metal‐Based Films

Abstract

Noble metal nanostructured films are of great interest for various applications including electronics, photonics, catalysis, and photocatalysis. Yet, structuring and patterning noble metals, especially those of the platinum group, is challenging by conventional nanofabrication. Herein, an approach based on solution processing to obtain metal‐based films (rhodium, ruthenium (Ru) or iridium in the presence of residual organic species) with nanostructuration at the 20 nm‐scale is introduced. Compared to existing approaches, the dual functionality of block‐copolymers acting both as structuring and as reducing agent under inert atmosphere is exploited. A set of in situ techniques has allowed for the capturing of the carbothermal reduction mechanism occurring at the hybrid organic/inorganic interface. Differently from previous literature, a two‐step reduction mechanism is unveiled with the formation of a carbonyl intermediate. From a technological point of view, the materials can be solution‐processed on a large scale by dip‐coating as polymers and simultaneously structured and reduced into metals without requiring expensive equipment or treatments in reducing atmosphere. Importantly, the metal‐based films can be patterned directly by block‐copolymer lithography or by soft‐nanoimprint lithography on various substrates. As proof‐of‐concept of application, the authors demonstrate that nanostructured Ru films can be used as efficient catalysts for H2 generation into microfluidic reactors.

High-Entropy-Alloy Nanocrystal Based Macro- and Mesoporous Materials

“…Carbon oxide and carbon dioxide can be also issued from this reduction process, as the oxidized products of the radical reaction, or can be produced by an alternative reduction path, such as the one suggested by Gayard et al in their study about the formation of mesoporous noble metal films. 49 In summary, porous latex-templated HEA-based particles can be fully reduced and crystallized at relatively low annealing temperatures (350 °C for the PMMA-templated macro-and mesoporous particles and 500 °C for PS-templated mesoporous particles). These results represent a significant advancement in the synthesis of HEAs, showing that spraydrying is a valuable technique for the facile bottom-up production of porous HEA-based particles.…”

“…These two steps are partially superimposed; we observe, in fact, that the PMMA depropagation occurs even below 330 °C, when the MS signal from the HCl reaches its maximum value. Carbon oxide and carbon dioxide can be also issued from this reduction process, as the oxidized products of the radical reaction, or can be produced by an alternative reduction path, such as the one suggested by Gayard et al in their study about the formation of mesoporous noble metal films …”

In situ infrared spectroscopic ellipsometry as a tool to probe the formation of sol–gel based mesoporous films

“…For in situ studies, this is particularly appropriate for identifying reaction intermediates. [58] UV-vis-NIR ellipsometry IR ellipsometry…”

Self-Regulating VO2 Photonic Pigments

“…The variation of IR transmittance as a function of the temperature was measured on thin films composed of VO 2 photonic particles spray-dried onto double polished Si substrates (transparent to the IR). The samples were characterized by a Woolam IR-VASE ellipsometer equipped with programmable heating stage (Linkam Scientific) . The temperature was cycled between 30 and 100 °C with a rate of 5 °C min –1 , a rate of temperature change that is realistic for applications as paints and textile.…”

“…The samples were characterized by a Woolam IR-VASE ellipsometer equipped with programmable heating stage (Linkam Scientific). 59 The temperature was cycled between 30 and 100 °C with a rate of 5 °C min −1 , a rate of temperature change that is realistic for applications as paints and textile. Spectra were recorded between 7937 and 250 cm −1 and were acquired every 5 °C.…”