Photocatalytic technology utilizing abundant solar light holds great promise to tackle many challenging environmental and energy issues. In recent years, various types of photocatalysts have been developed that are active for environmental purification and hydrogen production. Papers reporting preparation, characterization and photocatalytic testing of binary, ternary and quaternary compounds have been reviewed. The present review focuses on photocatalyst materials which adopt a defect pyrochlore structure. Starting with a brief introduction to semiconductor-based photocatalysts for environmental clean-up and hydrogen generation from water splitting, the development of high-efficiency UV and visible light driven photocatalysts belonging to the defect pyrochlore family is reviewed. The review covers all the defect pyrochlore photocatalysts studied so far, and provides guidance to researchers in this area for further investigation of these materials.

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A composite photocatalyst of N‐doped NaNbO3/V‐doped NaNbO3 was fabricated through a solid state method, hydrothermal process and a facile physical grinding. The composite and its counter parts were characterized by powder X‐ray diffraction, UV‐Vis‐diffuse reflectance spectroscopy, scanning and transmission electron microscopies and photoluminescence spectroscopy. The photocatalytic properties of N‐NaNbO3/V‐NaNbO3 were evaluated by the photocatalytic degradation of methyl violet dye under visible light. The photocatalytic activity of the composite is much higher than that of pure NaNbO3, N‐NaNbO3 and V‐NaNbO3. The higher photocatalytic activity of the N‐NaNbO3/V‐NaNbO3 composite is closely related to the restraining the recombination of electron–hole pairs at the interfaces of the N‐NaNbO3 and V‐NaNbO3. The possible charge transfer across the interface was also discussed based on the results of scavenger tests. This newly constructed N‐NaNbO3/V‐NaNbO3 composite could find potential applications in environmental purification and solar energy conversion with promising visible light‐driven photocatalytic activity and good stability.