Sludge-derived biochar nanotexture to construct BC/TiO₂ composite with metallic elements influential effect for efficient photocatalytic hydrogen evolution

Well-designed sewage sludge (SS) based multi-layered biochar (BC) template to construct BC/TiO₂ heterojunction with the influential effect of metallic elements for stimulating photocatalytic H₂ production has been investigated under several parameters including, calcination process, sacrificial reagent type, catalyst loading, and irradiation time. It was observed that biochar has an excellent structure with several metallic elements (M = Ni, Cu, Mn, Zn, and Fe), enabling efficient charge separation. The novel biochar made from sewage sludge incorporated TiO₂ played a key role in H₂ production via photocatalytic water splitting. The highest H₂ production of 2523 μmol h⁻¹ g⁻¹ was achieved using BC/TiO₂, suggesting 5.50 times more activity than pure TiO₂. This obvious enhancement in productivity was due to the synergetic effect of biochar metallic elements, and the defect structure of biochar during the binary synthesis process by developing a several-layer structure, which enabled the efficient charge carrier separation. The presence of several metals boosted the synergy between TiO₂ and biochar and increased the electron transfer rate. Furthermore, recycling experiments for 12 h proved the high catalyst stability to promote continuous H₂ evolution. As a result, the innovative BC/TiO₂ nanocomposite provided a simple technique for increasing electron transport carriers while enhancing strong interfacial contacts for optimal sustainable energy generation.