Insights into the Performance of Co_xNi_1–xTiO₃ Solid Solutions as Photocatalysts for Sun-Driven Water Oxidation

Abstract

CoNiTiO systems evaluated as photo- and electrocatalytic materials for oxygen evolution reaction (OER) from water have been studied. These materials have shown promising properties for this half-reaction both under (unbiased) visible-light photocatalytic approach in the presence of an electron scavenger and as electrocatalysts in dark conditions in basic media. In both situations, CoNiTiO exhibits the best performance and is proved to display high faradaic efficiency. A synergetic effect between Co and Ni is established, improving the physicochemical properties such as surface area and pore size distribution, besides affecting the donor density and the charge carrier separation. At higher Ni content, the materials exhibit behavior more similar to that of NiTiO, which is a less suitable material for OER than CoTiO.

Porous NiTiO3/TiO2nanostructures for photocatatalytic hydrogen evolution

“…[20][21][22] However, the synthesis of such mixed oxides in the form of high surface area materials is extremely challenging, what has limited advances in this direction. [23][24][25][26][27] To overcome this severe challenge, we present here a simple, high throughput and scalable hydrothermal-based strategy to produce porous NiTiO3/TiO2 heterostructures. This strategy is based on the synthesis of needle bundles of Ni-doped TiO2 (TiO2:Ni) and their posterior sintering in air to produce highly crystalline NiTiO3/TiO2 heterostructures with a significant level of porosity reminiscent of the large density of interfaces within the needle bundles.…”

Copper-Substituted NiTiO3 Ilmenite-Type Materials for Oxygen Evolution Reaction

“…SEM images reveal micrometer-sized grains for all Ni 1– x Cu x TiO 3 compositions, as expected for oxides synthesized by the solid-state reaction at high temperature (Figure S1). Contrary to Co 1– x Ni x TiO 3 , the solid solution studied here is not continuous in the whole composition range but limited to 20 mol % in copper ( x = 0.2). Indeed, for a copper content higher than x = 0.25, simple oxides (TiO 2 and NiO-type) are systematically detected in addition to a major NiTiO 3 -type phase whatever the annealing temperature used.…”

“…Ilmenite oxides appear attractive in this context, but the reported NiTiO 3 OER catalysts presented high overpotentials. Partial substitution of Ni with Co was recently proposed as an effective strategy to decrease overpotentials in these materials, but these remained significantly higher than state-of-the-art OER catalysts …”

Metal Titanate (ATiO3, A: Ni, Co, Mg, Zn) Nanorods for Toluene Photooxidation under LED Illumination

“…NiTiO 3 sample has a bandgap energy of 2.6 eV and absorption peaks at 448, 505, 744 nm, again justifying the sample's yellow color. Furthermore, the peaks at 448 nm and 505 nm are associated with electron transfer from Ni 2+ to Ti 4+ [69]. The separation efficiency of photo-generated charge carriers is revealed through photoluminescence (PL) spectroscopy.…”