Photocharged Water Splitting Employing a Nickel(II) Tellurium Oxide (Photo)anode in Alkaline Medium

Abstract

Nickel-based oxides and (oxy)­hydroxides are known to be electrocatalytically active for the oxygen evolution reaction (OER) in an alkaline medium. However, the aforementioned materials would be more auspicious, especially for photoelectrocatalysis, if their optical properties fell within the range of the solar spectrum. These properties could be attained by either doping or by creating a specific crystal structure. In this study nickel­(II) tellurium oxide was synthesized by employing the Pechini sol–gel synthesis route and calcined at 400 °C (NTO-400), 600 °C (NTO-600), and 800 °C (NTO-800). It was physically characterized and (photo)­electrochemically tested for the OER in alkaline medium. Under electrocatalytic (EC) conditions, NTO-600 displayed the lowest overpotential, 353 mV, to drive a current density of 10 mA cm–2 and exhibited the lowest charge transfer resistance of 20.75 Ω. Under photoelectrocatalytic (PEC) conditions, NTO-600 (with a bandgap of 2.50 eV) realized a current density increase of 55% compared to pure EC conditions. Remarkably, this current density gain is (to a greater extent) maintained, subsequent to the termination of illumination, which points to photocharging of the material and the subsequent utilization of the stored charge to drive the OER (in the dark). Solar energy conversion, storage, and subsequent utilization is therefore realized through the use of nickel­(II) tellurium oxide.

Hydrothermal Synthesis of Ni3TeO6 and Cu3TeO6 Nanostructures for Magnetic and Photoconductivity Applications

“…The appearance of NiTe 2 O 5 in low amount can be ascribed to the calcination step, taking into account that this phase can be generated by the Ni 3 TeO 6 decomposition at high temperature. 25,40 This fact highlights the relevance of using synchrotron radiation XRD to characterize the crystalline structure of inorganic materials. 41 The CTO_H samples (Figure 1b) show characteristic diffraction peaks at 2θ = 20.93, 25.90, 30.10, 37, 25, 43.42, 54.07, 56.52, 63.48, 70.05, and 76.377°, which correspond to the characteristic peaks of (200), (211), (220), ( 222), (400), (422), (431), (440), (600), and (622) lattice planes of Cu 3 TeO 6 (PDF 01-074-1255), respectively, related to the Cu 3 TeO 6 crystalline single phase.…”

Synthesis of Anatase/Brookite Mixed Phase TiO2 Nanostructures and its Photocatalytic Performance Study

“…Recently, advanced oxidation processes (AOPs) have been proposed as alternative methods for the elimination of many toxic organic compounds present in wastewater, air, and soil. [6][7][8][9] Among the various AOPs, a photocatalytic process using a semiconductor as photocatalyst under UV-visible light has been extensively used for the oxidation of various refractory organic and inorganic compounds. This technique have been reported by many researchers for complete degradation as well as mineralization of the organic pollutants present in the air and water.…”

Annealed Polycrystalline TiO2 Interlayer of the n-Si/TiO2/Ni Photoanode for Efficient Photoelectrochemical Water Splitting

“…Great effort has been made to develop various metal oxides with photocatalytic properties. 8,9 Both a highly catalytic reaction and high photovoltage/photocurrent generation are important for the material to achieve efficient energy conversion. However, it is challenging for a material to meet the above two conditions at the same time.…”

“…Photoelectrochemical (PEC) water splitting is an attractive way to convert solar energy to renewable hydrogen fuel. − Electrons and holes are generated by a semiconductor from absorbing sunlight and driven to the electrode surface in an electrolyte to drive the water splitting reaction. Great effort has been made to develop various metal oxides with photocatalytic properties. , Both a highly catalytic reaction and high photovoltage/photocurrent generation are important for the material to achieve efficient energy conversion. However, it is challenging for a material to meet the above two conditions at the same time.…”

“…As a result, it affects charge and photovoltage generation. Various interface layer designs have been introduced between these two materials to optimize both photovoltage generation and the catalytic reaction. − Ni is one of the earth-abundant materials that offers high oxygen evolution reaction activity. An ultrathin Ni film coating on an n-Si was reported to generate high photovoltage (500 mV) by inducing large band bending in n-Si .…”