For Ti-doped hematite photoanodes, high temperature annealing drastically increases the water oxidation plateau photocurrent, but also induces an anodic shift of onset potential by about 100 m V, thus hindering the pe...For Ti-doped hematite photoanodes, high temperature annealing drastically increases the water oxidation plateau photocurrent, but also induces an anodic shift of onset potential by about 100 m V, thus hindering the performance under low applied bias. To the best of our knowledge, the effects of high temperature annealing on the onset potential have been rarely studied. Herein, both X-ray photoelectron spectroscopy（XPS） measurements and theoretical calculations indicated that the increase of surface Ti/Fe atomic ratio after high temperature annealing decreased the adsorption capacity of hydroxide ions on the hematite surface. Subsequently, the flatband potential（i.e., the theoretical onset potential） of Ti doped hematite photoanodes positively shifted, which was supported by the Mott-Schottky measurements.展开更多
A state-of-the-art overview of N-dopant characterizations in nano-TiO_(2)second-generation photocatalysts is provided.The related literature is very rich and sometimes offers contrasting interpretations.Here we critic...A state-of-the-art overview of N-dopant characterizations in nano-TiO_(2)second-generation photocatalysts is provided.The related literature is very rich and sometimes offers contrasting interpretations.Here we critically discuss up-to-date literature results and our own findings,as retrieved by several experimental(BET,HR-TEM,XPS,DRS,HR-XRPD,EXAFS,electrochemical tools)and theoretical(periodic DFT)techniques.Our intent is to pull together outcomes from very different and complementary sources to make an as much as possible coherent picture of the morphological,electrochemical and electronic properties of N-TiO_(2)materials.It is commonly accepted that critical issues to be considered in the design of high-performing N-TiO_(2)photocatalysts are synthetic strategy,defect concentration and chemical nature of the lattice point defects.We focus on the latter two issues,with emphasis on sol-gel prepared materials,according to the specific area of expertise of our group.The problem of the chemical nature of guest N species into the lattice is crucial,as substitutional(N_(s))or interstitial(N_(i))nitrogen place their valence states just above the valence band or deeper into the band gap.Overall,we show how synergism among experimental and theoretical techniques is decisive to disentangle structural,electronic and morphological effects in complex N-doped TiO_(2)matrices.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21473090, U1663228)
文摘For Ti-doped hematite photoanodes, high temperature annealing drastically increases the water oxidation plateau photocurrent, but also induces an anodic shift of onset potential by about 100 m V, thus hindering the performance under low applied bias. To the best of our knowledge, the effects of high temperature annealing on the onset potential have been rarely studied. Herein, both X-ray photoelectron spectroscopy（XPS） measurements and theoretical calculations indicated that the increase of surface Ti/Fe atomic ratio after high temperature annealing decreased the adsorption capacity of hydroxide ions on the hematite surface. Subsequently, the flatband potential（i.e., the theoretical onset potential） of Ti doped hematite photoanodes positively shifted, which was supported by the Mott-Schottky measurements.
文摘A state-of-the-art overview of N-dopant characterizations in nano-TiO_(2)second-generation photocatalysts is provided.The related literature is very rich and sometimes offers contrasting interpretations.Here we critically discuss up-to-date literature results and our own findings,as retrieved by several experimental(BET,HR-TEM,XPS,DRS,HR-XRPD,EXAFS,electrochemical tools)and theoretical(periodic DFT)techniques.Our intent is to pull together outcomes from very different and complementary sources to make an as much as possible coherent picture of the morphological,electrochemical and electronic properties of N-TiO_(2)materials.It is commonly accepted that critical issues to be considered in the design of high-performing N-TiO_(2)photocatalysts are synthetic strategy,defect concentration and chemical nature of the lattice point defects.We focus on the latter two issues,with emphasis on sol-gel prepared materials,according to the specific area of expertise of our group.The problem of the chemical nature of guest N species into the lattice is crucial,as substitutional(N_(s))or interstitial(N_(i))nitrogen place their valence states just above the valence band or deeper into the band gap.Overall,we show how synergism among experimental and theoretical techniques is decisive to disentangle structural,electronic and morphological effects in complex N-doped TiO_(2)matrices.
