Black silicon with controllable macropore array for enhanced photoelectrochemical performance

Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO₂ by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.