In-Situ Synthesis of Nb2O5/g-C3N4 Heterostructures as Highly Efficient Photocatalysts for Molecular H2 Evolution under Solar Illumination

Faryal Idrees,Muhammad Tahir,Detlef Bahnemann,Ralf Dillert,Faheem Butt

doi:10.3390/catal9020169

Faryal Idrees, Muhammad Tahir + Show 3 more

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https://doi.org/10.3390/catal9020169

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Abstract

This work focuses on the synthesis of heterostructures with compatible band positions and a favourable surface area for the efficient photocatalytic production of molecular hydrogen (H2). In particular, 3-dimensional Nb2O5/g-C3N4 heterostructures with suitable band positions and high surface area have been synthesized employing a hydrothermal method. The combination of a Nb2O5 with a low charge carrier recombination rate and a g-C3N4 exhibiting high visible light absorption resulted in remarkable photocatalytic activity under simulated solar irradiation in the presence of various hole scavengers (triethanolamine (TEOA) and methanol). The following aspects of the novel material have been studied systematically: the influence of different molar ratios of Nb2O5 to g-C3N4 on the heterostructure properties, the role of the employed hole scavengers, and the impact of the co-catalyst and the charge carrier densities affecting the band alignment. The separation/transfer efficiency of the photogenerated electron-hole pairs is found to increase significantly as compared to that of pure Nb2O5 and g-C3N4, respectively, with the highest molecular H2 production of 110 mmol/g·h being obtained for 10 wt % of g-C3N4 over Nb2O5 as compared with that of g-C3N4 (33.46 mmol/g·h) and Nb2O5 (41.20 mmol/g·h). This enhanced photocatalytic activity is attributed to a sufficient interfacial interaction thus favouring the fast photogeneration of electron-hole pairs at the Nb2O5/g-C3N4 interface through a direct Z-scheme.

Highlights

IntroductionDue to certain limitations of the most frequently employed photocatalyst, TiO2, many other photocatalysts have been developed and explored for photocatalytic molecular H2 evolution
Renewable energy sources are currently needed by our society to address the foreseable future energy crisis and growing environmental issues
Nb2 O5 (NBO) and Nb2 O5 /g-C3 N4 (NBCN) heterostructures were synthesized via a hydrothermal synthesis considering its possible principal advantages such as: (a) attaining porous structures with synthesis considering its possible principal advantages such as: (a) attaining porous structures with high surface areas; (b) reagents mixing at the atomic level, and (c) high reaction rates at a low reaction high surface areas; (b) reagents mixing at the atomic level, and (c) high reaction rates at a low reaction temperature due to the atomic mixing level [23,24,25]

Summary

Introduction

Due to certain limitations of the most frequently employed photocatalyst, TiO2, many other photocatalysts have been developed and explored for photocatalytic molecular H2 evolution. Their significant limitations are the high recombination rate of photogenerated electron-hole pairs and unfavorable band edges, their low photocatalytic activity. Cu2 O are thought of as good alternatives but their stability and effective light absorption present additional additionalissues. Issues.Somehow, Somehow,these theseissues issueshave havebeen been solved solved by by adopting adopting the the atomic atomic layer layer deposition deposition (ALD). The non‐toxicity, facile synthesis, high visible light (ALD) technique and doping, etc. The non-toxicity, facile synthesis, high visible light absorption

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