Contents lists available at ScienceDirect Surfaces and Interfaces journal homepage: www.elsevier.com/locate/surfin Hydrogen production through photoreforming of methanol by Cu (s) /TiO 2 nanocatalyst: Optimization and simulation Zahra Shams Ghamsari, Hadis Bashiri ⁎ Department of Physical Chemistry, Faculty of Chemistry, University of Kashan, Kashan, Iran ARTICLE INFO Keywords: Kinetic Monte Carlo Simulation Nano photocatalyst Hydrogen generation Response surface methodology TiO 2 ABSTRACT In this research, photocatalytic generation of hydrogen from methanol has been investigated in a solution containing TiO 2 nanoparticles either with or without Cu ions using kinetic Monte Carlo simulation and response surface methodology. The obtained mechanism and the kinetic parameters of this process were confrmed by the good qualitative correspondence between the simulated and the experimental data. The RSM based on the central composite design (CCD) has been used to study the main square and interaction of independent variables initial concentration of methanol, irradiation, time of reaction, Cu concentration, and TiO 2 concentration. According to the results, the time of reaction is the most infuential variable with a positive efect on hydrogen generation efciency. Increasing Cu ions to the solution until a certain amount has a positive impact on hy- drogen generation efciency, and then, it has a negative impact. Using KMC and RSM together, the optimum conditions were provided in which the efciency of hydrogen production increases about fourteen times com- pared with the empirical one. 1. Introduction In recent years, hydrogen has become a clean and renewable en- ergy. Hydrogen production from non-fossil fuels is very important be- cause of the energy consumption increasing, population growth, and the probability of energy crisis in the world. The abundance of the primary resources, the low releasing of pollutants, the reversibility of production cycle, and the decreasing of greenhouse efects are the properties that make hydrogen an especial fuel. Hydrogen can be generated through clean ways without air pollution increasing [1]. The sacrifcial reactants for H 2 production are divided to the organic and inorganic reactants [2].S 2− /SO 3 2– , Fe 2+ ,H 2 S, Br – ,I – , CN – , and Ce 3+ are some examples of the inorganic sacrifcial reactants, and al- cohols, acids, aldehydes, and sugars are the examples of organic ones. Cargnello et al. [2] discussed the recent developments in the use of the biomass-derived oxygenated compounds, such as methanol, ethanol, glycerol, and sugars. Photocatalytic degradation of alcohol is a neat way for hydrogen generation. In this process, irradiation to photo- catalyst separates the electrons, and the remained positive holes are the strong oxidants. Methanol is largely used as sacrifcial agent in photo- catalysis, and it is attractive compound due to its high reactivity, structural simplicity, and absence of C–C bonds [2]. Photogenerated electrons react with the protons and produce hydrogen molecules. TiO 2 nano photocatalyst is a highly active pho- tocatalyst. It is a remarkable catalyst in hydrogen production from al- cohol due to its biological and chemical characteristics, being nontoxic, its high photocatalytic activity and its stability. Due to electron-hole recombination, TiO 2 nanostructures generally exhibit the low hydrogen production efciencies. To decrease the electron-hole recombination, two diferent approaches are mainly used: 1) A sacrifcial organic agent is adding to the reacting solution. It reacts with photogenerated positive holes and prevents electron-hole re- combination. 2) Using metal particles such as Rh, Au, Pt, Ni, Pd, and Cu on the TiO 2 surface inhibits electron-hole recombination. The Fermi levels of these metals are lower than that of TiO 2 , and the electrons can be transferred to them, while the holes remain on the TiO 2 . Therefore, the possibility of electron-hole recombination is reduced. The availability, cheapness, and high efciency of hydrogen gen- eration are the reasons which make methanol and Cu species as the suitable compounds for hole scavenger and TiO 2 surface modifer, re- spectively [3-7]. Choi and Kang [8] showed that the CuO species on the surface of anatase TiO 2 improve the H 2 production via methanol/water photodecomposition. In another study [9], they found the H 2 https://doi.org/10.1016/j.surfn.2020.100709 Received 5 July 2020; Received in revised form 17 September 2020; Accepted 20 September 2020 ⁎ Corresponding author. E-mail address: hbashiri@kashanu.ac.ir (H. Bashiri). Surfaces and Interfaces 21 (2020) 100709 Available online 23 September 2020 2468-0230/ © 2020 Elsevier B.V. All rights reserved. T