Environmentally effective photocatalyst CoO–TiO2 synthesized by thermal precipitation of Co in amorphous TiO2

•CoO–TiO2 is 16–24 times more effective than TiO2, it is sunlight active at room temperature.•Co-photocatalysis enhances the degradation potential of well known catalyst (e.g., TiO2).•CoO is a very powerful co-photocatalyst to enhance the activity of TiO2.•Co-TiO2 degrades paraoxon into p-nitrophenol and p-benzoquinone under environmental conditions.