Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece Research Paper Enhanced photocatalytic activity of nanoporous BiVO 4 /MCM-41 co-joined nanocomposites for solar energy conversion and environmental pollution abatement Brundabana Naik ⁎ ,1 , Binita Nanda ⁎ ,1 , Kundan Kumar Das 1 , Kulamani Parida ⁎ ,1 Centre for Nanoscience and Nanotechnology, Institute of Technical Education and Research, Siksha ‘O’ Anusandhan University, Bhubaneswar 751030, Odisha, India ARTICLE INFO Keywords: Photocatalysis O 2 evolution BiVO 4 MCM-41 Dye degradation ABSTRACT BiVO 4 /MCM-41 nanocomposite photocatalysts were prepared by hydrothermal reaction taking bismuth nitrate and ammonium vanadate as precursors. Different wt% of BiVO 4 (2.5, 5 and 10 wt%) have been loaded on nanoporous MCM-41 supports and also the hydrothermal synthetic time has been varied to design a series of photocatalysts. XRD suggests well formation of crystalline BiVO 4 , TEM confirms small sized BiVO 4 nanocrystals uniformly distributed on nanoporous MCM-41 support, UV–vis DRS and PL indicates red shift and lower re- combination of BM nanocomposites. The photocatalytic water splitting to generate O 2 and toxic organic dye (Rh 6G) degradation studies have been evaluated using these efficient nanocomposite photocatalysts. 5 wt% BiVO 4 / MCM-41@4 h (BM-4) catalyst shows the best results in both O 2 generation (691.3 μmol in 4 h) and 98% of Rhodamine 6G degradation respectively. The enhanced photocatalytic activity may be attributed to nanoporous architecture, quantum size of BiVO 4 , high surface area, better light harvestation and electron transfer. 1. Introduction Photocatalytic water splitting into hydrogen and oxygen in the visible region of the solar spectrum to meet the current global clean energy need is a promising approach for researchers [1–3]. Despite the first report of photo-electrochemical water splitting by Fujishima and Honda in long back 1972, a practical solar powered system is still not feasible at present due to (i) the economic impracticability of the photocatalyst (ii) low solar to fuel conversion efficiency in visible range and (iii) photo stability [4]. The thermodynamic uphill photocatalytic water splitting reaction requires 238 kJ/mol energy. Over the years, TiO 2 based photocatalyst [5], doped TiO 2 [6–8], other semiconductor oxides [9,10] and per- ovskites [11], hetero-junction photocatalyst [12], dye sensitized pho- tocatalyst [13], plasmonic photocatalyst [14,15] and inorganic hybrid nanostructured catalyst [16–23] have been studied. However quantum efficiency and photo stability is a big problem for the traditional pho- tocatalyst. Hence, an alternative semiconductor, a BiVO 4 photocatalyst, has gained huge attention owing to its large light harvestment for ab- sorption (band gap of 2.4 eV) [24]. Intense absorption in visible range, high photo stability, inexpensive and environmentally benign character of BiVO 4 makes it a potential alternative candidate for better visible light activity [25]. The low band gap of BiVO 4 is due to the overlap of Bi 6 s and O 2p anti-bonding states resulting a significant rise of valence band [26]. Among several polymorphs of BiVO 4, tetragonal and monoclinic sheelite structure have been preferred for photocatalysis owing to its crystal orientation [27]. However the fast recombination rate of charge carriers of BiVO 4 lowers the quantum efficiencies. To enhance the quantum efficiency, lower size BiVO 4 crystallites (lower than the hole diffusion length) and higher surface area with nanoporous architecture is preferred. The zero dimensional (0 D) BiVO 4 quantum dots have advantages of small size and size tunable optoelctronic, large surface area, short and effective charge transfer length which may en- hance photocatalytic activity. However, the self-aggregation behavior of quantum dots and high surface defects and large recombination rate limit the practical applications [28]. To enhance photo activities of the BiVO 4 quantum dots, loading these in a 2 D or 3 D nanoporous support may resolve the issue [12]. Therefore MCM-41, a 3D mesoporous mo- lecular sieves having large surface area can be an interesting support material for enhanced catalytic activity. In the present invention, we have synthesized BiVO 4 /MCM-41 co- joined nano-composite photocatalyst by varying the weight percentage of BiVO 4 loaded on MCM-41 support and hydrothermal synthetic time. We have thoroughly studied the photocatalytic organic pollutant http://dx.doi.org/10.1016/j.jece.2017.08.045 Received 6 June 2017; Received in revised form 13 August 2017; Accepted 28 August 2017 ⁎ Corresponding authors. 1 All the authors have contributed equally. E-mail addresses: brundabananaik@soauniversity.ac.in (B. Naik), binitananda@soauniversity.ac.in (B. Nanda), kulamaniparida@soauniversity.ac.in (K. Parida). Journal of Environmental Chemical Engineering 5 (2017) 4524–4530 Available online 31 August 2017 2213-3437/ © 2017 Elsevier Ltd. All rights reserved. MARK