This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The...This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The TiO2@MOF core-shell n anorod array is formed by coati ng an 8 nm thick MOF layer on a vertically aligned TiO2 nanorod array scaffold via a layer-by-layer self-assembly method. This vertically aligned core-shell nanorod array enables a long optical path length but a short path length for extraction of photogenerated minority charge carriers (holes) from TiO2 to the electrolyte. A p-n junction is formed between TiO2 and MOF, which improves the extraction of photogenerated electr ons and holes out of the TiO2 nano rods. In additi on, the MOF coati ng sign ificantly improves the efficie ncy of charge in jecti on at the photoanode/electrolyte interface. Introduction of Co(lll) into the MOF layer further enhances the charge extraction in the photoanode and improves the charge injection efficiency. As a result, the photoelectrochemical cell with the TiO2@Co-MOF nanorod array photoanode exhibits a photocurrent density of 2.93 mA/cm^2 at 1.23 V (vs. RHE), which is ~ 2.7 times the photocurrent achieved with bare T1O2 nanorod array under irradiation of an unfiltered 300 W Xe lamp with an output power density of 100 mW/cm^2.展开更多
文摘This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The TiO2@MOF core-shell n anorod array is formed by coati ng an 8 nm thick MOF layer on a vertically aligned TiO2 nanorod array scaffold via a layer-by-layer self-assembly method. This vertically aligned core-shell nanorod array enables a long optical path length but a short path length for extraction of photogenerated minority charge carriers (holes) from TiO2 to the electrolyte. A p-n junction is formed between TiO2 and MOF, which improves the extraction of photogenerated electr ons and holes out of the TiO2 nano rods. In additi on, the MOF coati ng sign ificantly improves the efficie ncy of charge in jecti on at the photoanode/electrolyte interface. Introduction of Co(lll) into the MOF layer further enhances the charge extraction in the photoanode and improves the charge injection efficiency. As a result, the photoelectrochemical cell with the TiO2@Co-MOF nanorod array photoanode exhibits a photocurrent density of 2.93 mA/cm^2 at 1.23 V (vs. RHE), which is ~ 2.7 times the photocurrent achieved with bare T1O2 nanorod array under irradiation of an unfiltered 300 W Xe lamp with an output power density of 100 mW/cm^2.
