Facile construction of nanowires via etching process to increase heterostructure area for efficient photocatalysis

•Core-shell Si/TiO2 nanowires were synthesized vertically on silicon substrate.•The heterostructure owned a wide spectral absorption with large photocurrent.•The catalytic efficiency of the sample was 86.82% in 1 h with good stability.•The excited charges were effectively separated by the internal electric field.