“Ti2C MXene and NiTe Based Heterojunction: A Novel Approach to Photoelectrochemical Water Splitting and Carbon Dioxide Reduction”

Abstract

The development of effective and sustainable strategies for energy conversion and carbon dioxide (CO₂) reduction is pivotal in tackling pressing global energy and environmental issues. This research focuses on a novel heterojunction composed of titanium carbide (Ti₂C) MXene and nickel telluride (NiTe), designed for photoelectrochemical (PEC) water splitting and CO₂ reduction applications. The synthesized material was thoroughly characterized using several techniques, including Powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), Raman Spectroscopy, UV-Visible Diffuse Reflectance Spectroscopy (DRS), X-Ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and Fourier Transform Infrared Spectroscopy (FTIR). TEM analysis revealed that the NiTe structure exhibited needle like features extending from the 2D sheets of Ti₂C MXene, indicating robust interfacial interactions and confirming the successful formation of the heterojunction. The Ti₂C-NiTe heterostructure, referred to as MNT, demonstrated superior performance metrics, including the lowest charge transfer resistance (RCT), reduced band gap, and the highest photocurrent density. Specifically, the MNT heterojunction achieved an impressive photocurrent density of 11.7 mA cm⁻² at 1.8556 V vs. RHE, with an RCT value of 422.3 Ω, a flat band potential (VFB) of 0.79 V, and an extended electron lifetime of 1.97 milliseconds. Additionally, it exhibited a specific surface area of 31.629 m²/g, a band gap of 2.94 eV, and notable CO₂ reduction activity, producing carbon monoxide at a rate of 5.173 mmol g⁻¹ h⁻¹ and methane at 0.214 mmol g⁻¹ h⁻¹ at 400 °C. These results indicate the successful formation of a Schottky heterojunction, which enhances charge carrier mobility and minimizes charge recombination by establishing a Schottky barrier.