Molecular precursor pathway to Co1−xNixNb2O6 for photocatalytic dye degradation: Optical and charge transport studies

Lozančić, Ana; Vrankić, Martina; Razum, Marta; Pavić, Luka; Androš Dubraja, Lidija; Jurić, Marijana (2025) Molecular precursor pathway to Co1−xNixNb2O6 for photocatalytic dye degradation: Optical and charge transport studies. Journal of the American Ceramic Society, 108 (7). ISSN 0002-7820

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Abstract

A new approach for the formation of binary and ternary mixed metal oxides, namely, CoNb2O6, NiNb2O6, and Co0.5Ni0.5Nb2O6, through a modified single-source molecular precursor route was investigated. By optimizing the annealing temperature, heating/cooling rates and holding times, the phase compositions of thermal processing of mixtures of oxalate-based complexes [M(bpy)3]2[NbO(C2O4)3]Cl·nH2O (M = Co2+ (1) or/and Ni2+ (2); n = 11, 12) and (NH4)3[NbO(C2O4)3]·3H2O (3) were evaluated. Phase-pure columbite oxides Co1−xNixNb2O6 (x = 0, 0.5, and 1) were obtained in one step by heating the mixtures of two (1 and 3, or 2 and 3) or three oxalate complexes (1 and 2 and 3) at 1200°C for 10 h with a heating/cooling rate of 10°C min−1. The (micro)structure, morphology, and optical properties of the as-prepared materials were characterized by powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FE-SEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). Impedance spectroscopy was used to investigate the electrical and dielectric properties, providing valuable insights into the charge transport dynamics. The CoNb2O6 exhibits the greatest conductivity in the series (2.64 × 10−11 Ω−1 cm−1 at 120°C), two orders of magnitude greater than those of NiNb2O6 and Co0.5Ni0.5Nb2O6. The ternary oxide Co0.5Ni0.5Nb2O6 has a minimum in conductivity and dielectric loss, but it shows a maximum in dielectric permittivity. Estimated band gap energies of CoNb2O6, NiNb2O6, and Co0.5Ni0.5Nb2O6 within the visible light excitations prompt us to investigate their photocatalytic activities in the degradation of the methylene blue (MB) dye under visible light irradiation without and with hydrogen peroxide (H2O2). It is evident that the Co1−xNixNb2O6/H2O2 systems exhibit higher photocatalytic activity: the degradation efficiency of MB was found to be between 26% and 38%. In addition, the cyclic stability of the photocatalyst was investigated and a possible proposed photocatalytic degradation mechanism was substantiated by a scavenger analysis study.

Item Type:	Article
Uncontrolled Keywords:	columbite niobate-based oxides; electrical properties; (micro)structural characterization; molecular precursors; photocatalytic activity
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Materials Chemistry Division of Materials Physics
Projects:	Project title Project leader Project code Project type Topološka raznolikost oksalatnih spojeva: sinteza, svojstva i upotreba za okside-TOPOXAL-SYPROXID Marijana Jurić; Lidija Kanižaj; Damir Pajić; Pavla Šenjug IP-2019-04-5742 HRZZ Otvorene znanstvene infrastrukturne platforme za inovativne primjene u gospodarstvu i društvu-O-ZIP David Matthew Smith KK.01.1.1.11.0001 EK
Depositing User:	Lorena Palameta
Date Deposited:	26 Jun 2025 11:14
URI:	http://fulir.irb.hr/id/eprint/9878
DOI:	10.1111/jace.20485

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