(Invited) In Depth Analysis of the Promotion of Ni on Mg:SrTiO 3 By CrO x

• Published in: Meeting abstracts (Electrochemical Society) Vol. MA2020-01; no. 39; p. 1705
• Main Authors: Mul, Guido, Han, Kai, Haiber, Diane, Cherevko, Serhiy, Crozier, Peter A, Mei, Bastian Timo
• Format: Journal Article
• Language: English
• Published: 01.05.2020
• ISSN: 2151-2043; 2151-2035
• DOI: 10.1149/MA2020-01391705mtgabs

Ni/NiO-Mg:SrTiO 3 is a promising formulation for the overall splitting of water to H 2 and O 2 when illuminated with light of 365 nm. The preparation prescribes various steps, including solid state synthesis of MgO/TiO 2 , followed by mixing with SrCO 3 and calcination at 1100 C for 10 h. Ni@NiO is deposited by impregnation, calcination, reduction in H 2 , and passivation with O 2 . When CrO x is finally photodeposited on such composite, a significant enhancement of the performance is observed, both in activity and stability. A steady state apparent quantum yield at 365 nm of no less than 38% is obtained. The composition of the photo-active material was investigated using state-of-the-art electron microscopy and elemental analysis, which demonstrates that CrO x is photodeposited in the vicinity of several, but not all Ni/NiO particles. This is explained by the inhomogeneity in interfacial contact between the Ni/NiO particles and the Mg:SrTiO 3 substrate, affecting the probability of reduction of Cr(VI)-species during the photodeposition process. In situ ICP shows various elements of the composite catalyst leach into solution, including Sr, Mg and Ni. CrO x reduces leaching of Ni/NiO from Ni/NiO-Mg:SrTiO 3 , which might explain the enhanced stability of CrO x containing composites. The mechanism of activation of the catalyst by photodeposition of CrO x and suggestions for further improvement in the preparation cycle of the composite catalyst, are discussed.