New spinel oxide catalysts for visible-light-driven water oxidation

Abstract

Nanoscale Co-Mn-Ga spinels are promoted by the ''synergistic'' interaction of Co and Mn, thus paving the way to tailored and flexible catalyst design concepts for visible-light-driven water oxidation.

Visible‐Light‐Driven Water Oxidation with Nanoscale Co3O4: New Optimization Strategies

“…Water oxidation activity was evaluated according to standard [Ru-A C H T U N G T R E N N U N G (bpy) 3 ] 2 + /S 2 O 8 2À protocols. [32] First, a suspension was prepared by mixing oxide photocatalyst (24.08 mg, 0.1 mmol), [RuA C H T U N G T R E N N U N G (bpy) 3 ]Cl 2 photosensitizer (16.17 mg, 21.6 mmol), and NaS 2 O 8 (25.67 mg, 0.11 mmol) in 20 mL Na 2 SiF 6 buffer (20 mm Na 2 SiF 6 , pH 6) in a dark cabinet. The suspension was then degassed with helium to remove O 2 in both solution and in the head vial.…”

“…Generally, the structural flexibility of spinel-type oxides is an asset for the tuning of site occupancies, oxidation states, and dopant contents toward higher catalytic activity. [31][32][33][34][35][36] On the other hand, the comprehensive surface, structural, and morphological characterization of a given spinel-based material quickly turns into a demanding task that requires numerous complementary analytical techniques, especially for complex and mixed-valent compounds. UV/Vis spectroscopic analyses, for example, impressively demonstrate the diver-Abstract: Water oxidation is the "bottleneck" of artificial photosynthesis on the way to clean and sustainable solar fuels production.…”

Nonstoichiometric oxygen in Mn–Ga–O spinels: reduction features of the oxides and their catalytic activity

“…7 Of special interest are Mn-containing oxides with a spinel structure that possess a high thermal stability and are able to intercalate additional cations. The catalytic properties of Mncontaining oxides were examined in different processes: Mn-Co oxides are promising for the oxidation of CO, propene, 8 and benzyl alcohol, 9 as materials for fuel cells and oxygen reduction/ evolution electrocatalysts; 10,11 Ga-Co-Mn can be employed for visible-light-driven water oxidation; 12 Mn-Al spinels are precursors of the active component of catalysts for the oxidation of CO and hydrocarbons; 13 Zn-Mn-Al oxides are used for the reduction of nitrobenzene to nitroazobenzene; 14 and Mn-Fe as Fenton catalysts toward catalytic degradation of highly concentrated methylene blue. 15 The spinel structure is described by a general formula AB 2 O 4 , where A is a divalent cation, and B is a trivalent one.…”

Co/Mn‐Oxides for Visible‐Light‐Driven Photocatalytic Water Oxidation

“…This “synergistic” effect was correlated with a high amount of surface oxygen species and the presence of mixed valent M II /M III (M = Co, Mn) centers. Parallel studies on spinel‐type Al‐ and Ga‐matrices furthermore revealed an influence of the main group cations on the catalytic performance 1.…”