Application of nanomaterials in dark or light-assisted fermentation for enhanced biohydrogen production: A mini-review

Biohydrogen is regarded as the most promising new generation of green energy. However, the low yield and high cost of biohydrogen restrict its production on a large scale. Nanomaterials have demonstrated outstanding potential for improving biohydrogen production due to their unique photoelectrochemical properties. Some metal nanoparticles are used to promote biohydrogen production in dark fermentation (biohydrogen increased by 5.4-230 %). The state-of-the-art involves using metal or nonmetal photosensitizers to build extracellular or intracellular photo-biohybrid systems with microorganisms, which can be driven by light to efficiently produce biohydrogen (increased by 1.29-8.6 times). This review has summarized in detail the application status and working principle of metal nanoparticles in dark fermentation, the light-assisted biohydrogen production performance, and the mechanism of the extracellular and intracellular photo-biohybrid system. Next, the toxicity and biocompatibility modifications of nanoparticles were discussed. Finally, we proposed the key issues that should be prioritized in the long-term development of biohydrogen.