Structural Properties of NdTiO_2+xN_1–x and Its Application as Photoanode

Abstract

Mixed-anion inorganic compounds offer diverse functionalities as a function of the different physicochemical characteristics of the secondary anion. The quaternary metal oxynitrides, which originate from substituting oxygen anions (O 2– ) in a parent oxide by nitrogen (N 3– ), are encouraging candidates for photoelectrochemical (PEC) water splitting because of their suitable and adjustable narrow band gap and relative negative conduction band (CB) edge. Given the known photochemical activity of LaTiO 2 N, we investigated the paramagnetic counterpart NdTiO 2+ x N 1– x . The electronic structure was explored both experimentally and theoretically at the density functional theory (DFT) level. A band gap ( E g ) of 2.17 eV was determined by means of ultraviolet–visible (UV–vis) spectroscopy, and a relative negative flat band potential of −0.33 V vs reversible hydrogen electrode (RHE) was proposed via Mott–Schottky measurements. 14 N solid state nuclear magnetic resonance (NMR) signals from NdTiO 2+ x N 1– x could not be detected, which indicates that NdTiO 2+ x N 1– x is berthollide, in contrast to other structurally related metal oxynitrides. Although the bare particle-based photoanode did not exhibit a noticeable photocurrent, Nb 2 O 5 and CoO x overlayers were deposited to extract holes and activate NdTiO 2+ x N 1– x . Multiple electrochemical methods were employed to understand the key features required for this metal oxynitride to fabricate photoanodes.

Hydrophobic signature on TiO2 nanoparticles in liquid water

“…52 Since LaTiO2N is not as hygroscopic as TiO2, all these signals of surface OH/H2O species can be observed directly, without special sample preparation. Moreover, the chemical shifts of isolated hydroxyl species at around 1.3 ppm as predicted in our MD-DFT/GIPAW calculations for both, positively and negatively charged anatase (101) surfaces, were in agreement with previous fast MAS NMR studies of semiconductors and photocatalysts: BaTiO3, [53][54][55][56] NdTiO2N, 57 and CaTaO2N. 58 To conclude, we presented a 1 H MAS NMR spectrum of TiO2 nanoparticles under fully hydrated conditions, where signals corresponding to details of the solid-liquid interface could be resolved.…”

Doping of Nonmetal Se in Fe2O3 Nanowire Array-Based Photoanodes for Water Oxidation

“…EIS measurements as a function of potential were performed in the dark for understanding the intrinsic electronic properties of the α-Fe 2 O 3 film in electrolyte solution. We used the common Mott–Schottky equation to calculate the flat-band potential ( E fb ) and carrier concentration ( N d ) in the thin film electrode where C refers to the interfacial capacitance, N d means the number of donors, and E is the applied voltage; the meaning of other symbols is explained in ref . The Mott–Schottky plot recorded from α-Fe 2 O 3 film photoanodes is presented in Figure a.…”

“…As displayed in Figure 6b, all samples showed a sharp rise in photocurrent and subsequently dropped by a rapid exponential decay and settled at a constant value. The rapid change in current upon illumination switching, which originates from photogenerated charge recombination and PEC water oxidation by holes at the electrode/electrolyte interface, 31 is very common for many typical photoelectrodes. On the contrary, the cathodic spikes arose upon switching illumination off and decayed rapidly and settled to a stable value.…”

A Minireview on the Role of Cocatalysts in Semiconductor-Based Photocatalytic CH4 Conversion

“…As a clean and abundant resource, solar energy provides a potential way to drive not only downhill reactions but also uphill reactions even at low temperature. , The driving force originates from the fact that the photogenerated charge carriers with strong redox capability can initiate the activation of CH 4 and the photon energy can compensate the increase of Gibbs free energy for the reaction system . For the past several decades, photocatalysis has been extensively explored for water splitting, , CO 2 reduction and environmental remediation .…”