Two infrequent organic hybrid transition metal hexa-sulfide electro-catalysts for the efficient oxygen evolution reaction

The exploration of the cheap oxygen evolution reaction (OER) electro-catalysts together with high efficient activity is highly imperative for obtaining clean and renewable hydrogen energy. Herein, two novel organic hybrid transition metal hexa-sulfide electro-catalysts [TM(S6)(tptz)] [TM = Zn (1) and Mn (2), tptz = 2,4,6-tris-2pyridyl-1,3,5-triazine] with rare poly-sulfur S-6(2-) anion was isolated from the facile solvothermal reaction of sulfur powder, transition metal salt and tptz in anhydrous ethanol at 120 degrees C for 7 days. Both 1 and 2 are isostructural and show a distorted trigonal-pyramidal stereochemistry with chelate S-6(2-) anion and large pi-conjugated aromatic tptz. 1 and 2 are used in combination with Ni nanoparticles and porous Ni foam (NF) to fabricate a 1/Ni/NF or 2/ Ni/NF electrode as OER electro-catalyst, which delivers excellent OER activity with the low overpotential (233 mV for 1/Ni/NF and 241 mV for 2/Ni/NF at 10 mA center dot cm(-2)) and small Tafel slope (45.9 mV center dot dec-1 for 1/Ni/NF and 50.7 mV center dot dec(-1) for 2/Ni/NF) in KOH alkaline electrolyte, and is evidently superior to the well-known OER electrocatalyst RuO2.