Conformal Carbon Nitride Coating as an Efficient Hole Extraction Layer for ZnO Nanowires‐Based Photoelectrochemical Cells

Abstract

Charge transfer at the semiconductor–electrolyte junction is one of the main challenges for further improvement of photoelectrochemical (PEC) water splitting cells due to the poor surface catalytic properties of most semiconductors for the water oxidation reaction. Here it is shown, for the first time, that a conformal and thin carbon nitride (CN) layer can efficiently extract holes from ZnO nanowires (NWs), leading to a great enhancement of both PEC performance and stability in alkaline solution. The conformal CN coating is acquired by using a new synthetic method which involves the deposition of small supramolecular assemblies on ZnO‐NWs as a seeding layer for the CN growth. Detailed PEC characterization reveals that the CN facilitates the hole transfer from the ZnO‐NWs to the electrolyte and acts as a protective shell, resulting in 3.5 times higher current densities and high external quantum efficiencies at 1.23 V versus RHE compared to the pristine ZnO‐NWs.

Tailoring a Zinc Oxide Nanorod Surface by Adding an Earth‐Abundant Cocatalyst for Induced Sunlight Water Oxidation

“…XPS spectra for 6d‐FeOOH(Gly)/ZnONR electrodes showed two spectral components at 401.2 eV and 399.2 eV binding energies (Figure S2), which are characteristics of glycine in the condensed phase and have been associated with −NH 2 and −NH 3 + groups, respectively . Both amino groups form N−H⋅⋅⋅O hydrogen bonds with oxygen atoms on ZnO surfaces.…”

“…The C1s photoemission signal in the 6d‐FeOOH(Gly)/ZnONR sample splits into two peaks. The first one, at 287.4 eV, is attributed to the secondary carbon atom from glycine, while that at 285.1 eV is assigned to the C=O bond from carboxyl groups . Thus, this organic compound can favor the dispersion of FeOOH nanoparticles and act as a thin film layer covering the ZnO surface nanorods.…”

Kohlenstoffnitridmaterialien für photochemische Zellen zur Wasserspaltung

“…Die in Abbildung 3d argestellten Abscheidungsverfahren umfassen Schmelzen auf flachen [38,39] oder TiO 2 -beschichteten Substraten. [85] Der In-situ-Gastransportmechanismus erlaubt eine vollständige Beschichtung des mesoporçsen TiO 2 -Films durch Erhitzen von pulverfçrmigen Vorstufen, die nur mit der Oberfläche des Films in Kontakt stehen. [85] Der In-situ-Gastransportmechanismus erlaubt eine vollständige Beschichtung des mesoporçsen TiO 2 -Films durch Erhitzen von pulverfçrmigen Vorstufen, die nur mit der Oberfläche des Films in Kontakt stehen.…”

“…Eine Klassifizierung und Hauptmerkmale der wesentlichen Syntheseverfahren sind in Tabelle S1 in den Hintergrundinformationen zusammengefasst. B. nanodrahtbeschichtete Substrate (entweder durch Aufbringen des Pulvers direkt über der Anordnung oder nach einem Einwirkschritt zur Erzeugung von "Keimen" der molekularen Vorstufen) [85] und mesoporçsesTiO 2 . Beispielef ürT echniken,b ei denen supramolekulare Anordnungen zur Herstellung von CN-Filmen auf Elektroden verwendet wurden.…”

Improved Utilization of Sunlight Through the Incidence Dependence of the Photonic Stop Band: A g‐C3N4‐Embedded Fluorine‐Doped Tin Oxide (FTO) Photonic Crystal Film

“…The optimization of light absorption and conversion, charge carrier separation and transportation are the critical factors for improving the performance of a solar energy conversion device. To this end, efforts such as doping,, and nanostructuring the photoactive materials,, adding co‐catalysts or sacrificial reagent have been made, and solar energy conversion devices with improved performance are therefore obtained. While an alternative strategy to pursue these improvements is using both the nature of materials and the nature of nature (the sun).…”