Single 2D MXene precursor-derived TiO2 nanosheets with a uniform decoration of amorphous carbon for enhancing photocatalytic water splitting

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Abstract

A high visible-light active TiO2 photocatalyst was prepared by simultaneously constructing ordered nanosheet structure and decoration of a homogeneous carbon layer from a single 2D MXene precursor. The TiO2 nanosheets/C composite exhibited a boosted photocatalytic activity under visible light condition up to three times of benchmark Degussa P25. It was revealed that the high photocatalytic activity can be ascribed to three major aspects. One was that the stacked nanosheets with ordered structure inherited from the 2D MXene, endowed a favorable electron-hole separation and transportation. The second was the decoration of carbon layer that evidently extended the absorption to more visible light region. Besides, the carbon layer also facilitated the separation and migration of photogenerated carriers. The proposed in-situ carbonization strategy with a uniformly decoration on TiO2 with remarkable visible light photocatalytic activity would greatly promote the wide application of TiO2 such as in photocatalytic water splitting.

Introduction

Since the splitting of water on TiO2 photoelectrodes was firstly discovered by Fujishima and Honda [1], semiconductor-based photocatalysis has attracted extensive attention [[2], [3], [4], [5]]. A variety of photocatalysts have been developed for light-driven hydrogen evolution [6], e.g., metal-oxides, nitrides, sulfides, phosphides, and their alloys [[7], [8], [9], [10], [11], [12], [13], [14]]. Among them, due to the high photocatalytic activity and chemical stability, TiO2 has been widely studied in the photocatalytic fields [[15], [16], [17], [18]]. However, the limited light absorption (λ < 390 nm) and fast recombination of photogenerated electron-holes of pristine TiO2 seriously hamper its wide applications [[19], [20], [21], [22], [23]].

In order to improve the utilization of light, many strategies have been used to extend the spectral response of TiO2 into the visible region and suppress the high recombination rate of photogenerated carriers to improve its photocatalytic performance, such as element doping and coupling of other semiconducting or conductive materials, such as quantum dots and nanostructured carbon [[24], [25], [26], [27], [28], [29]]. Notably, it has been reported that TiO2/carbon nanotubes and TiO2/graphene composites showed enhanced photocatalytic performances because of effective separation of photogenerated carriers and/or improved visible light response [26,30]. In general, the current TiO2/carbon composites were often prepared based on physical mixing and carbonization [31,32]. Therefore, it often tends to cause uneven distribution of carbon materials, forming local carbon material aggregates, making them the recombination center of photo-generated carriers, reducing the utilization of light [33]. Hence, how to achieve uniform dispersion of carbon in the TiO2/C composite has become the key to solving the above problems and improving the light utilization efficiency.

Herein, we report a novel way to obtain high visible light responsive TiO2 nanosheets/C composites from a single 2D MXene precursor, i.e. Ti3C2Tx (T = OH, F and O). Due to carbon source was homogeneously distributed in the precursor (MXene) at atomic level, the as-prepared TiO2 nanosheet-based composites could be obtained with a uniform dispersion of carbon. In addition, the TiO2 nanosheet/C composite inherited the ordered structural features of 2D MXene materials, which facilitates photocarrier migration. Therefore, it exhibited excellent photocatalytic activity under visible light. Compared with the benchmark TiO2 nanoparticles (P25), the photocatalytic hydrogen evolution efficiency of as-prepared TiO2 nanosheet/C composite increased by 3 times under visible light irradiation. Control experiments and mechanism studies showed the homogeneous dispersion of carbon on TiO2 and the formation of ordered nanosheets by using the 2D MXene precursor played vital roles.

Section snippets

Materials

TiC (99.9 %, 2–4 μm) and Ti (99.9 %, <48 μm) power were purchased from Aldrich. Al power (99.5 %, 48 μm) was obtained from Beijing Zhongnuo New Materials Co., Ltd (China). Hydrofluoric acid (HF, 40 wt %) was purchased from Aldrich. P25 was purchased from Evonik-Degussa (Germany). Glucose (AR) was obtained from Sinopharm Chemical Reagent Co., Ltd.

Synthesis of Ti3AlC2

Starting powers of TiC (2–4 μm), Al (<48 μm) and Ti (<48 μm) in a 1.8:1:1 M ratio was mixed in a mixer for 24 h. The mixture was put into electric tube

Results and discussions

As shown in Fig. 1, the TiO2 nanosheet/C composite was briefly prepared through two-step oxidation process based on 2D metal carbide (Ti3AlC2), which has a layered structure (Fig. 2a). After Ti3AlC2 was treated by HF, the disappearance of Al layer and the layered structure can be obviously observed in SEM image (Fig. 2b). When the layered Ti3C2Tx was further hydrothermally treated at 200 °C for 6 h, some TiO2 nanoparticles were emerged (Fig. S1a). Then, the layer-stacked TiO2/C composite,

CRediT authorship contribution statement

Jianhai Wang: Conceptualization, Methodology, Formal analysis, Investigation, Data curation, Writing - review & editing. Yanfei Shen: Resources, Formal analysis, Writing - review & editing. Songqin Liu: Resources, Formal analysis. Yuanjian Zhang: Conceptualization, Writing - review & editing, Supervision, Project administration.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (21775018, 21675022), the Natural Science Foundation of Jiangsu Province (BK20170084), the Open Funds of the State Key Laboratory of Electroanalytical Chemistry (SKLEAC201909), and the Fundamental Research Funds for the Central Universities. We also thank Prof. Z. M. Sun (SMSE, Southeast University) for offering Ti3AlC2 samples.

References (42)

  • A. Mills et al.

    Water purification by semiconductor photocatalysis

    Chem. Soc. Rev.

    (1993)
  • H. Kisch

    Semiconductor photocatalysis for chemoselective radical coupling reactions

    Acc. Chem. Res.

    (2017)
  • K. Maeda et al.

    Photocatalyst releasing hydrogen from water

    Nature

    (2006)
  • Y. Wang et al.

    Nanostructured VO2 photocatalysts for hydrogen production

    ACS Nano

    (2008)
  • X. Lu et al.

    Efficient photocatalytic hydrogen evolution over hydrogenated ZnO nanorod arrays

    Chem. Commun.

    (2012)
  • L. Yuliati et al.

    Highly active tantalum (v) nitride nanoparticles prepared from a mesoporous carbon nitride template for photocatalytic hydrogen evolution under visible light irradiation

    J. Mater. Chem.

    (2010)
  • M. Yoshida et al.

    ATR-SEIRAS investigation of the fermi level of Pt cocatalyst on a GaN photocatalyst for hydrogen evolution under irradiation

    J. Am. Chem. Soc.

    (2009)
  • Q. Li et al.

    Highly efficient visible-light-driven photocatalytic hydrogen production of CdS-cluster-decorated graphene nanosheets

    J. Am. Chem. Soc.

    (2011)
  • J. Zhang et al.

    Enhanced photocatalytic hydrogen production activities of Au-loaded ZnS flowers

    ACS Appl. Mater. Interface

    (2011)
  • S. Cao et al.

    Highly efficient photocatalytic hydrogen evolution by nickel phosphide nanoparticles from aqueous solution

    Chem. Commun.

    (2014)
  • J.F. Callejas et al.

    Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles

    ACS Nano

    (2014)
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