Nanohybrid photocatalysts in dye (Colorants) wastewater treatment: Recent trends in simultaneous dye degradation, hydrogen production, storage and transport feasibility

Dyes (colorants) are produced globally owing to their need in textile industries and this has led to the release of toxic dye effluents into environment. This is one of the major phenomena causing harmful effects on both human and aquatic organisms. In this review, the simultaneous and sustainable way of dye degradation with both wastewater treatment and hydrogen energy production via photocatalysis was discussed. It was seen that multiple researches were reported on different photocatalysts synthesis and experimentation on dye degradation and hydrogen production. This review further focuses on dyes and their toxicity, photocatalytic materials, hydrogen storage and transport feasibility. Magnetic biochar based photocatalysts showed more than 90% methylene blue degradation efficiency. Metal doped nano catalysts showed 0.072 min−1 rate of organic dye degradation. Hydrogen produced from photocatalysis needs to be safely stored and transported. Containers make and material for effective hydrogen storage and transport needs to be identified in future. This review recommends the future directions to overcome the limitations of existing photocatalysts for simultaneous dye degradation and hydrogen production.