Artificial Photosynthesis Using Semiconductor Nanomaterials

The mitigation of steadily increasing atmospheric CO2 might well be the major global scientific challenge of the twenty-first century. Carbon capture is an important issue in Alberta, a jurisdiction with a large carbon footprint. The use of CO2 as a feedstock for energy storage is also of interest. An efficient sunlight-driven CO2 reduction process that produces alcohols or hydrocarbons from H2O+CO2 can store energy in the form of chemical bonds - an alternative to hydrogen-based energy storage. Natural photosynthesis is the chemical reaction on which life is based, but is inefficient in terms of conversion of light into chemical energy (global efficiency ~0.2%). Semiconductor nanomaterial-based artificial photosynthesis will enable efficiencies several times higher than natural photosynthesis. Artificial photosynthesis is complex with eight electron transfer steps, thus rendering the reaction vulnerable to energetic losses at every step. The mechanistic routes governing the formation of desirable end-products are not fully established. And yet, there is huge potential; the combination of government levied carbon taxes (ALBERTA: currently $20/tonne of CO2, set to increase to $30/tonne by 2018 and CANADA: $50/tonne of CO2 by 2020) and highly efficient catalysts can render CO2 reduction profitable in the not-too-distant future. Companies that package and sell carbon offsets to big and small CO2 emitters are very interested in this technology.

2D C-N Semiconductors: Graphitic, Earth-Abundant Photocatalysts with Tunable Bandgaps

Karthik Shankar, Ujwal Thakur, Pawan Kumar, Ehsan Vahidzadeh

Conference/Workshop

Application of TiO2 Nanotubes and Nanowires in Photocatalytic CO2 Reduction

Karthik Shankar, Ujwal Thakur, Piyush Kar

Conference/Workshop

Au-Nanoparticle Embedded TiO2 Nanotube Arrays for Sensing, Photocatalysis and Nonlinear Optics

Karthik Shankar

Conference/Workshop

CO2 reduction performance of TiO2 nanotube-based heterojunction photocatalysts

Karthik Shankar, Ehsan Vahidzadeh, Piyush Kar

Conference/Workshop

Chalcogenide Semiconductor Nanomaterials for Photocatalytic Applications

Karthik Shankar, Ujwal Thakur, Piyush Kar

Conference/Workshop

Charge Separation and Transport in Functional Heterojunctions Based on Solution-Grown TiO2 Nanotube & Nanowire Arrays

Karthik Shankar

Conference/Workshop

Copper Sulfide Nanostructures and their utility in Photocatalytic CO2 Reduction

Karthik Shankar, Piyush Kar, Yun Zhang

Conference/Workshop

Enhancing Photocatalyst and Solar Cell Performance Using Nanophotonic Effects

Karthik Shankar, Ujwal Thakur, Sheng Zeng, Piyush Kar

Conference/Workshop

Exploiting Nanophotonics and Plasmonic Hot Electrons for the Production of Solar Fuels

Karthik Shankar, Ehsan Vahidzadeh, Sheng Zeng, Ajay Manuel

Conference/Workshop

Highly Structured Nanomaterials for High Performance Photocatalysts and Solar Cells

Karthik Shankar

Conference/Workshop

Novel Materials for Clean and Sustainable Energy CHALLENGE PROGRAM WORKSHOP

Karthik Shankar

Conference/Workshop

One-Dimensional Solution-Processed TiO2 Nanostructures for Use in Photovoltaics, Photocatalysis, and Microwave Resonator Sensors

Karthik Shankar, Ryan Kisslinger, Ujwal Thakur, Najia Mahdi, Piyush Kar, Benjamin Wiltshire

Conference/Workshop

Optical Modelling of Non-Lithographically Fabricated Photonic Crystal- and Plasmonic- Photocatalysts

Karthik Shankar, Collin VanEssen, Ehsan Vahidzadeh, Sheng Zeng, Piyush Kar, Ajay Manuel, Yun Zhang

Conference/Workshop

Preferentially Oriented Zn-Doped TiO2 Nanotubes Grown on Non-Native Substrates

Karthik Shankar, Ryan Kisslinger, Ujwal Thakur

Conference/Workshop

Solution Processed Earth-Abundant Semiconductor Nanostructures for Sensing, Photocatalysis and Photovoltaics

Karthik Shankar

Conference/Workshop

TiO2 Nanotube - Noble Metal Nanoparticle Heterojunction Photocatalysts for CO2 Reduction

Karthik Shankar, Natalia Semagina, Jing Shen, Ehsan Vahidzadeh, Piyush Kar, Yun Zhang

Conference/Workshop

TiO2 nanotube and nanorod arrays: Playgrounds to study unusual heterojunctions, hot electron phenomena and nanophotonic effects

Karthik Shankar

Conference/Workshop

Visible Light Responsive, Earth-Abundant Heterojunction Photocatalysts

Karthik Shankar

Conference/Workshop

A Review on Photocatalytic CO2 Reduction using Perovskite Oxide Nanomaterials

Karthik Shankar, Ujwal Thakur, Sheng Zeng, Piyush Kar

Scholarly Refereed Journal

All-solid-state formation of titania nanotube arrays and their application in photoelectrochemical water splitting

Karthik Shankar, Pawan Kumar, Najia Mahdi, Yun Zhang

Scholarly Refereed Journal

Arrays of TiO2 nanorods embedded with fluorine doped carbon nitride quantum dots (CNFQDs) for visible light driven water splitting

Karthik Shankar, Ryan Kisslinger, Sahil Patel, Ujwal Thakur, Pawan Kumar, Kazi Alam, Sheng Zeng, Piyush Kar

Scholarly Refereed Journal

C3N5: A Low Bandgap Semiconductor Containing an Azo-linked Carbon Nitride Framework for Photocatalytic, Photovoltaic and Adsorbent Applications

Karthik Shankar, Ujwal Thakur, Pawan Kumar, Kazi Alam, Ehsan Vahidzadeh, Najia Mahdi, Piyush Kar, Vladimir Michaelis, Ankur Goswami, Guy Bernard

Scholarly Refereed Journal

Characterization of Carrier Dynamics in Metal Oxide Nanostructures and Tellurophenes

Benjamin Wiltshire

Masters Thesis

Core-shell titanium dioxide-titanium nitride nanotube arrays with near-infrared plasmon resonances

Karthik Shankar, Najia Mahdi, Piyush Kar

Scholarly Refereed Journal

Distinguishing between deep trapping transients of electrons and holes in TiO 2 nanotube arrays using planar microwave resonator sensor

Karthik Shankar, Najia Mahdi, Mojgan Daneshmand

Scholarly Refereed Journal

Enhanced Charge Separation in g-C3N4–BiOI Heterostructures for Visible Light Driven Photoelectrochemical Water Splitting

Karthik Shankar, Ujwal Thakur, Pawan Kumar, Kazi Alam, Sheng Zeng, Piyush Kar

Scholarly Refereed Journal

Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity

Karthik Shankar, Ryan Kisslinger, Najia Mahdi, Piyush Kar, Yun Zhang

Scholarly Refereed Journal

Hexagonal Double Perovskite Cs2AgCrCl6

Arthur Mar, Karthik Shankar, Anton Oliynyk, Jan Poehls

Scholarly Refereed Journal

High Rate CO2 Photoreduction Using Flame Annealed TiO2 Nanotubes

Karthik Shankar, Ryan Kisslinger, Ujwal Thakur, Pawan Kumar, Kazi Alam, Ehsan Vahidzadeh, Sheng Zeng, Najia Mahdi, Piyush Kar, Ajay Manuel, Yun Zhang

Scholarly Refereed Journal

Melanin-based electronics: From proton conductors to photovoltaics and beyond

Karthik Shankar, Ehsan Vahidzadeh

Scholarly Refereed Journal

Nanophotonic enhancement and improved electron extraction in perovskite solar cells using near-horizontally aligned TiO2 nanorods

Karthik Shankar, Ryan Kisslinger, Sahil Patel, Ujwal Thakur, Pawan Kumar, Sheng Zeng, Piyush Kar, Yun Zhang, Al Meldrum, Ankur Goswami

Scholarly Refereed Journal

Optical Properties of Anatase and Rutile Phase TiO2 Nanotubes

Yun Zhang

Masters Thesis

Plexcitonics – Fundamental principles and optoelectronic applications

Karthik Shankar, Aaron Kirkey, Najia Mahdi, Ajay Manuel

Scholarly Refereed Journal

Sunlight-driven water-splitting using two dimensional carbon based semiconductors

Karthik Shankar, Pawan Kumar

Scholarly Refereed Journal

Triplet excitons: improving exciton diffusion length for enhanced organic photovoltaics

Karthik Shankar, Eric Rivard, Bruno Luppi, Manisha Gupta

Scholarly Refereed Journal