Unveiling the surface precipitation effect of Ag ions in Ag-doped TiO₂ nanofibers synthesized by one-step hydrothermal method for photocatalytic hydrogen production

Photocatalysis has been regarded as a promising process for pollution removal and green energy. TiO₂ nanofibers synthesized by the hydrothermal method presents high crystalline and performs excellently due to the efficient charge transport. For practical use, we designed an autoclave with a 1,000 cm³ of Teflon-liner inside and stainless steel outside for the hydrothermal synthesis of Ag/TiO₂ NFs. Various parameters of the process, including reaction temperature, doping concentration, and calcination temperature, were investigated to provide a reliable and optimal process. Through the hydrothermal reaction, TiO₂ particles transformed into sodium titanate nanorods, and further refilled the hollow channel. With the proton exchange using diluted hydrochloric acid, the precipitated Ag nanoparticles were leached but appeared again on the surface of Ag/TiO₂ nanofibers after the calcination. Silver incorporation enhanced the absorption in the visible region and precipitated onto the TiO₂ NFs surface after the optimal calcination, constructing the heterostructure. It dominated the photocatalytic performance of pollutant degradation and water splitting. The unveiling of silver surface precipitation gives a clear illustration in the scaled-up hydrothermal method of Ag/TiO₂, providing an efficient way for nanomaterial fabrication.