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N-Doped and Cu-doped TiO₂-B nanowires with enhanced photoelectrochemical activity

Su, Jingjie, Li, Zhaodong, Zhang, Yongquan, Wei, Yingjin, Wang, Xudong
RSC advances 2016 v.6 no.20 pp. 16177-16182
X-ray photoelectron spectroscopy, anodes, copper, crystal structure, electric current, electrical conductivity, electrochemistry, hot water treatment, light, lighting, microwave treatment, nanowires, oxidation, solar collectors, solar energy, titanium dioxide, ultraviolet radiation, wavelengths
TiO₂-B is a metastable phase of titania with an interesting crystal structure and electrochemical properties. N-Doped and Cu-doped TiO₂-B nanowires (NWs) were synthesized by hydrothermal and microwave-assisted hydrothermal methods, respectively. All the NWs are single crystal with the same crystal orientation regardless of the synthesis method and doping situation. The doped NWs together with their corresponding pristine NWs were fabricated into a photoelectrochemical (PEC) anode for water oxidation and their photoactivity performances were studied and compared under different illumination wavelength ranges. The Cu-doped TiO₂-B NWs exhibited a significantly higher photocurrent density than all the other samples under direct Xe lamp illumination; while their performance rapidly dropped below the hydrothermal NWs when the UV illumination was cut off. On the contrary, N-doped TiO₂-B NWs exhibited significantly enhanced photoactivity particularly in the visible light range. X-ray photoelectron spectroscopy revealed that N-doping could narrow the electronic bandgap of TiO₂, while the Cu-doping had little impact on the bandgap but rather improved the electrical conductivity. This research provides a new insight into elemental and phase control of TiO₂-based solar energy harvesters.