Recently there has been a growing interest on metal tungstate compounds for photo- and electro-catalytic applications.    Our previous study has revealed that cobalt tungstate (CoWO4) efficiently catalyzes oxygen evolution on electrodes at close to neutral pH.  Here we further examine its activity for photochemical water oxidation. In this reaction system, CoWO4 nanoparticles are suspended in buffer solution (pH 8) together with [Ru(bpy)3]2+ (light absorber) and Na2S2O8 (sacrificial electron acceptor).  Upon illumination with a xenon lamp, rapid oxygen evolution was observed using a Clark type oxygen sensor.  Control experiments showed that there was no O2 product in the absence of CoWO4, [Ru(bpy)3]2+ or Na2S2O8.  Under optimized conditions, the specific reaction rate of O2 evolution reached 16.4 mmol per gram of CoWO4 per sec. Turnover frequency is estimated in the order of 10 per sec., comparable to that of the well-known IrO2.

Cobalt tungstate as highly active catalyst for photochemical water oxidation

245th National Meeting (2013)

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