Energy and environmental concerns related to the use of fossil fuels have forced researchers to seek renewable and clean energy resources. The demand of this energy encourages to study artificial photosynthesis, in which high-energy compounds are produced from water as an electron donor, by utilizing solar energy [1,2,5]. In a quest to develop sustainable energy conversion processes, many research groups have attempted water splitting using sunlight, which occurs in two processes: water oxidation or oxygen evolution reaction (OER) and water reduction or hydrogen evolution reaction (HER). However, oxidation of water to produce O₂ is challenging from both thermodynamic and kinetic points of view, and thus, this process is considered too important for water splitting [3,4]. It is important to study the catalytic activity of different catalysts, especially when using sustainable and cheaper semiconductors for the oxidation of photoactivated water.

This work presents the synthesis, characterization of catalysts derived from nitroprussides as new materials for photocatalytic for oxygen evolution reaction [5]. Our attempts to use electrocatalysts derived from Nitroprussides (Np) M[Fe(CN)₅NO] where M = Fe²⁺, Mn²⁺, Co²⁺ and Ni²⁺, in photocatalytic water oxidation (pH 7.2) using [Ru(bpy)₃]²⁺ (bpy = 2,2'-bipyridine) as a sensitizer and Na₂S₂O₈ as an electron acceptor [2], will be discussed in this presentation.

References:

[1] Mohammad Mahdi Najafpour, Spideh Madadkhani, Mojtaba Tavahodi, Manganese oxides supported on nano-sized metal oxides as water-oxidizing catalysts for water-splithing systems: 3-Electrochemical studies, International Journal of Hydrogen Energy 42 (2017) 60-67.

[2] Yusuke Yamada, Kohei Oyama, Rachel Gates, and Shunichi Fukuzumi. High Catalytic Activity of Heteropolynuclear Cyanide Complexes Containing Cobalt and Platinum Ions: Visible-Light Driven Water Oxidation. Angew. Chem. Int. Ed. 2015, 54, 5613 –5617.

[3] Mingxing Chen, Yizhen Wu, Yongzhen Han, Xiaohuan Lin, Junliang Sun, Wei Zhang and Rui Cao. An Iron-based Film for Highly Efficient Electrocatalytic Oxygen Evolution from Neutral Aqueous Solution. ACS Appl. Mater. Interfaces 2015, 7, 21852−21859.

[4] Sara Goberna-Ferroń, WillintonY.Hernańdez, BarbaraRodríguez-García, and José Ramoń Galań-Mascaroś. Light-Driven Water Oxidation with Metal Hexacyanometallate Heterogeneous Catalysts. ACS Catal. 2014, 4, 1637−1641.

[5] L. Reguera, J. Balmaseda, C.P. Krap, and E. Reguera, Hydrogen Storage in Porous Transition Metals Nitroprussides, J. Phys. Chem. C2008, 112, 10490-10501.