Ge-Doped Cobalt Oxide for Electrocatalytic and Photocatalytic Water Splitting

Abstract

Cobalt oxides find widespread application in energy materials as oxygen evolution catalysts (OECs) in the oxygen evolution reaction (OER) and photocatalytic overall water splitting (OWS) reaction. However, the nature of the active cobalt species, their role in these reactions, and possible commonalities remain poorly understand. Here, the impact of (redox-inert) germanium dopants on the physicochemical properties of Co3O4 nanoparticles was investigated in electrochemical oxygen evolution and photocatalytic OWS reactions. A significant enhancement in OER performance on doping is attributed to the restructuring of spinel Co3O4 to serpentine Co3Ge2(OH)5, with the latter transforming to an oxyhydroxide active phase during OER. Combination of the p-type Co3Ge2(OH)5 semiconductor as an OEC with an n-type Bi0.5Y0.5VO4 semiconductor doubles the photocatalytic OWS activity of the latter, resulting in H2 and O2 productivities of ∼175.7 and ∼90.1 μmol/h, respectively. Formation of the composite semiconductor induces an intense internal electric field across the p–n junction, facilitating separation of photogenerated carriers and increased OWS activity, which is also validated in alternative photocatalyst, Al-doped SrTiO3. A similar transformation of serpentine Co3Ge2(OH)5 to an oxyhydroxide was not observed during OWS, indicating that Ge doping confers distinct advantages for electrochemical OER vs photocatalytic OWS.

Enhanced Photocatalytic Degradation Activity Using the V2O5/RGO Composite

“…Most of the organic compounds are carcinogenic in nature. In addition, water pollution directly leads to soil pollution, which directly or indirectly affects day-to-day life [ 1 , 2 ]. From the textile industries, synthetic colour dyes were released during the textile wash mix very well with water in comparison with the chemicals and reagents, so the mix of effluents has toxic properties.…”

Deciphering the photocatalytic hydrogen generation process of Fresnoite Ba2TiGe2O8 by electronic structure and bond analyses

“…8,9 To date, a great number of semiconductors have been studied as well as their combinations to form composites, which are beneficial for enhancing the light harvesting ability or decreasing the recombination rate of photo-excitons, thus achieving a high efficiency. [10][11][12][13][14][15][16] Anyway, developing new and highly efficient photocatalysts is always desired. In fact, most photocatalysts are composed of metal cations with d 0 (i.e.…”

Reshaping the material research paradigm of electrochemical energy storage and conversion by machine learning

“…Nowadays, electrochemical energy storage and conversion (EESC) devices have been increasingly used due to the ear theme of “Carbon Neutrality.” The key role of these devices is to temporarily store the intermittent electricity from renewable sources for reliable reconstruction of the energy structure with higher sustainability. In this regard, EESC could bridge renewable energy and worldwide sustainable demands 1–7 . For this purpose, advanced electrode materials and catalysts, the core of EESC devices, are urgently needed, which have attracted tremendous research efforts in the past decades.…”

“…In this regard, EESC could bridge renewable energy and worldwide sustainable demands. [1][2][3][4][5][6][7] For this purpose, advanced electrode materials and catalysts, the core of EESC devices, are urgently needed, which have attracted tremendous research efforts in the past decades. However, a series of troublesome challenges must be overcome for the development of these key materials.…”