Vladislav S. Kashansky, Alexander V. Sukhov, Angelina V. Zhurenok, Denis D. Mishchenko, Olga S. Soficheva, Ekaterina A. Kozlova, Oleg G. Sinyashin, Dmitry G. Yakhvarov, “Microwave-assisted synthesis of M/TiO$_2$/C (M = Ni, Cu, Ni–Cu) photocatalysts for CO$_2$ reduction: structural evolution and photocatalytic properties”, Nanosystems: Physics, Chemistry, Mathematics, 2025, Volume 16, Issue 6,Pages 865

CHEMISTRY AND MATERIAL SCIENCE

Microwave-assisted synthesis of M/TiO$_2$/C (M = Ni, Cu, Ni–Cu) photocatalysts for CO$_2$ reduction: structural evolution and photocatalytic properties

Vladislav S. Kashansky^ab, Alexander V. Sukhov^ab, Angelina V. Zhurenok^c, Denis D. Mishchenko^d, Olga S. Soficheva^a, Ekaterina A. Kozlova^c, Oleg G. Sinyashin^a, Dmitry G. Yakhvarov^ab

^a Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center RAS, Kazan, Russia
^b A. M. Butlerov Institute of Chemistry, Kazan Federal University, Kazan, Russia
^c Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia
^d Synchrotron Radiation Facility SKIF, Boreskov Institute of Catalysis, Kol'tsovo, Russia

Abstract: This study presents the synthesis of a TiO$_2$-based composite material with transition metal (Ni, Cu) nanoparticles using microwave radiation. The obtained materials were characterised using X-ray powder diffraction, and the size of the nanoparticles was determined using the Scherrer equation. The photocatalytic activity of the synthesised composites was studied in reaction of CO$_2$ reduction to CO and CH$_4$ under the visible light with a wavelength of 400 nm. Microwave treatment of a mixture of TiO$_2$ with transition metal salts (Ni, Cu) and graphite was founded to decrease a photocatalytic activity in CO$_2$ reduction reaction, while a mechanical mixture of TiO$_2$ and graphite, not subjected to microwave treatment, demonstrated increased catalytic activity compared to unmodified TiO$_2$ Evonik P25. The decrease in catalytic activity of the case of microwave-treated samples is associated with an irreversible phase transition of the photoactive anatase phase into the catalytically inert rutile phase and formation of TiO$_{2-x}$ phases. This process is induced by overheating during microwave synthesis, where graphite (C$_g$) acts as an effective microwave absorber and a reducing agent for Ti$^{4+}$ cations in TiO$_2$. The obtained results are interesting for the development of efficient TiO$_2$-based photocatalysts for CO$_2$ reduction.

Keywords: titanium dioxide, photocatalysis, transition metal nanoparticles, carbon dioxide reduction, X-ray diffraction, green chemistry.

Received: 02.10.2025
Revised: 24.10.2025
Accepted: 26.10.2025

Language: English

DOI: 10.17586/2220-8054-2025-16-6-865-871