Role of MIL-53(Fe)/hydrated–dehydrated MOF catalyst for electrochemical hydrogen evolution reaction (HER) in alkaline medium and photocatalysis† Ravi Nivetha, a Pratap Kollu, bc Krishna Chandar, d Sudhagar Pitchaimuthu, e Soon Kwan Jeong f and Andrews Nirmala Grace * a The role of breathing behavior in hydrated and dehydrated forms of MIL-53(Fe) is investigated here. The material can be used as an efficient electrocatalyst and photocatalyst for a hydrogen evolution reaction (HER) in an alkaline medium and the same was further tested for the degradation of organic pollutants. The as-synthesized MIL-53(Fe)/hydrated and dehydrated forms were characterized by different analytical techniques to study their structure, morphology, surface analysis, thermal, physical and chemical properties. The breathing behavior of the hydrated and dehydrated forms of MIL-53(Fe) was studied through BET surface analysis. Our results show a low onset potential (0.155 V and 0.175 V), Tafel slope (71.6 mV per decade, 88.7 mV per decade) and a large exchange current density (1.6  10 4 mA cm 2 and 2.5  10 4 mA cm 2 ). Hydrated and dehydrated MIL-53(Fe) degraded an RhB dye solution within 30 minutes thus proving their efficiency as efficient photocatalysts. 1. Introduction Molecular hydrogen is considered a future energy carrier in the transition from the current hydrocarbon economy and is regarded as a clean energy carrier with the highest gravimetric energy density. Hydrogen as a clean fuel has been produced from renewable energy sources. 1 There are diverse effective hydrogen production methods like water electrolysis, photolysis, thermolysis, hydrocarbon steam reforming, biomass pyrolysis, and coal gasication. 2–4 Among these methods, electrolysis and electrochemical splitting have been considered as simple eco-friendly methods. The electro- chemical hydrogen evolution reaction (HER) is one of the main cathodic reactions in electrochemical energy conversion devices. 5 To meet the requirements of a HER, efficient electrocatalysts are imperative owing to the multi electron nature of dihydrogen generation through proton reduction 6 and reduction of over potential (h). In general, electrocatalytic materials are found to the best solution for low production costs and reducing the over potential of a hydrogen evolution reaction (HER). Hence, it is an active eld of research for the development of new electrode materials in order to reduce the hydrogen evolution over potential at an acceptable current density. 7 In the past decades, various catalysts have been synthesized and reported. Among them, a Pt catalyst is the best candidate for a HER reaction, owing to its over potential and stability in an acid medium. 8 But its high cost and scar- city prevents its usage for further large scale hydrogen production. Thus, there is an urge for the development of alternative catalysts (e.g., non-noble and metal-free electro catalysts). Compared with metal-free electrocatalysts, porous materials are used as active catalyst materials because of their tunable molecular structures, abundance, and strong toler- ance to acidic/alkaline environments. 9,10 Metal organic frameworks (MOFs) are a family of crystalline porous solids with coordination networks of metal ions and organic ligands linked together, and have been used as an absorbing class of micro porous crystalline materials due to their intrinsic low density, large accessible pore volumes, tunable textures and well-dened pore size distributions. They have been studied for different applications in gas storage/separation, magne- tism, molecular recognition, proton and ion conduction, luminescence, catalysis, and drug carrying/delivery. Also, a Centre for Nanotechnology Research, VIT University, Vellore, India-632014. E-mail: anirmalagrace@vit.ac.in; anirmalagladys@gmail.com b Thin Film Magnetism Group, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, UK c School of Physics, University of Hyderabad, Gachibowli, Hyderabad 500046, India d Department of Physics, School of Advanced Sciences, VIT University, Vellore, Tamil Nadu 632014, India e Photocatalyst and Coatings Group, SPECIFIC, College of Engineering, Swansea University (Bay Campus), Fabianway, Swansea, SA18EN, UK f Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon, 305-343, South Korea † Electronic supplementary information (ESI) available. See DOI: 10.1039/c8ra08208a Cite this: RSC Adv. , 2019, 9, 3215 Received 4th October 2018 Accepted 15th December 2018 DOI: 10.1039/c8ra08208a rsc.li/rsc-advances This journal is © The Royal Society of Chemistry 2019 RSC Adv. , 2019, 9, 3215–3223 | 3215 RSC Advances PAPER Open Access Article. Published on 23 January 2019. Downloaded on 1/25/2019 11:44:03 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online View Journal | View Issue