Enhancing the Photoelectrochemical Performance of a Hematite Dendrite/Graphitic Carbon Nitride Nanocomposite through Surface Modification with CoFeO_x

Abstract

In this article, we report the surface modification of a hematite dendrite/graphitic carbon nitride composite (HD/g‐CN) with an oxygen evolution catalyst (OER), specifically CoFeOx, to achieve enhanced photoelectrochemical (PEC) water splitting under visible‐light irradiation. Such modified hematite dendrites are studied for the first time for PEC water splitting and demonstrate higher activity compared to unmodified composites. The synthesized composites are characterized by X‐ray diffraction spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FESEM) and elemental dispersive analysis (EDX). The photoelectrochemical performance was studied by linear sweep voltammetry (LSV) under visible‐light irradiation. The photoelectrochemical characterization reveals that the CoFeOx/HD/g‐CN composite shows a maximum photocurrent density of 0.60 mA cm−2 at 1.23 V versus RHE (reversible hydrogen electrode), which is comparable to the best reported value of hematite. A Mott–Schottky analysis demonstrates the formation of a p–n heterojunction of CoFeOx with the HD/g‐CN composite which is responsible for the enhanced PEC activity as a result of efficient separation of photogenerated electron–hole pairs.

Synergies of co-doping in ultra-thin hematite photoanodes for solar water oxidation: In and Ti as representative case

“…In this work, our goal is to increase the understanding of nanostructuring and co-doping in a a-Fe 2 O 3 model photoelectrode system for solar water splitting, which can then be further integrated into more complicated electrode architectures. 37,38 Doping methods and nanofabrication techniques are heavily investigated in regard to the effect on the nal performance, [38][39][40] but there is still ample room to investigate the exact mechanisms that cause the improvement: for example, it is well known that annealing improves the hematite water splitting efficiency, 22,41 but the diffusion of the dopant into the material from a substrate or a surface decoration as a consequence of the annealing, is investigated more rarely. 24,42,43 In parallel, when the dopant is the main subject of interest, controllable yet elaborate methods are employed.…”

An ultrathin cobalt–iron oxide catalyst for water oxidation on nanostructured hematite photoanodes

“…Despite several studies on the electrocatalytic activity of CoFeOx for water oxidation, few reports of this oxide on the surface of hematite have been described. [16][17][18][19] In these reports, the function of CoFeOx varies substantially depending on its thickness and the type of hematite used. In the present work, we deposited CoFeOx on nanocauliflower hematite photoanodes grown by atmospheric pressure chemical vapor deposition (APCVD).…”

Electrochemical reduction of CO2to ethylene on Cu/CuxO-GO composites in aqueous solution

“…In general, several researchers, including us, have preferred a layer by layer coating of electro-catalyst over the support material. 38,39 In contrast, few others have preferred a mixed form of the electrocatalyst and a support material 40 for studying the electro-catalysis. In order to study the effect of electrode fabrication strategy, electrodes fabricated in three different ways viz.…”