title: Gradient doping - a case study with Ti-Fe2O3towards an improved photoelectrochemical response.
abstract: The present study investigates the effect of gradient doping on modifying the photoelectrochemical response of Ti-doped Fe2O3photoanodes for their use in sunlight based water splitting for hydrogen evolution. The deposition of a thin film over the ITO (tin doped indium oxide) substrate was carried out using a spray pyrolysis method. The concentration of dopant was varied from 0.5-8.0 at% and two sets of samples were also prepared with low to high (0.5-8%) and high to low (8-0.5%) dopant concentrations in the direction towards the substrate. The prepared thin films were characterized using X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and UV-visible Spectroscopy. The photoelectrochemical studies revealed that the deposition of dopant layers with a low to high concentration towards the substrate exhibited a highly improved photoresponse (200 times) in comparison to the pristine sample and a two fold enhancement in comparison to 2% Ti-doped Fe2O3. The improvement in the photoresponse has been attributed to the values of a high flat band potential, low resistance, high open circuit voltage, carrier separation efficiency, applied bias photon-to-current conversion efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). A reduced charge transfer resistance has been demonstrated with Nyquist plots.
authors.affiliation: Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India. drsahabdas@gmail.com.
authors.forename: Anupam
authors.initials: A
authors.lastname: Srivastav
authors.affiliation: Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India. drsahabdas@gmail.com.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Verma
authors.affiliation: Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India. drsahabdas@gmail.com.
authors.forename: Anamika
authors.identifier: http://orcid.org/0000-0002-9704-8312
authors.initials: A
authors.lastname: Banerjee
authors.affiliation: Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Saif A
authors.initials: SA
authors.lastname: Khan
authors.affiliation: UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001, India.
authors.forename: Mukul
authors.initials: M
authors.lastname: Gupta
authors.affiliation: Department of Physics & Computer Science, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India.
authors.forename: Vibha Rani
authors.initials: VR
authors.lastname: Satsangi
authors.affiliation: Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India. drsahabdas@gmail.com.
authors.forename: Rohit
authors.initials: R
authors.lastname: Shrivastav
authors.affiliation: Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra 282005, India. drsahabdas@gmail.com.
authors.forename: Sahab
authors.initials: S
authors.lastname: Dass