Artificial Photosynthesis Using Semiconductor Nanomaterials

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Shining different lights on photocatalysis

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.

In the last four years of research, binary and ternary heterojunctions of the following four components have been shown by us to be particularly effective photocatalysts for artificial photosynthesis:

(i) Carbon nitrides: These are pi-conjugated polymers with a graphitic framework. They are easily exfoliated to form two-dimensional sheets. The leading member of this family is g-C3N4 whose bandgap of 2.6 eV is not optimal for solar energy harvesting. The Shankar Lab synthesized a new graphitic polymer with the chemical formula C3N5 which had a more optimal electronic bandgap of 1.7 eV. Information about the properties and performance of C3N5 was disseminated in a 2019 article in the prestigious Journal of the American Chemical Society in 2019 (https://doi.org/10.1021/jacs.9b00144) where it has since been cited over 200 times to date.

(ii) Plasmonic nanomaterials: Nanostructured coinage metals (Au, Ag, Cu) generate hot carriers that can be used to drive chemical reactions. However, hot carriers represent a short-lived exotic species and our research has advanced knowledge and understanding in this area. By controlling the shape, size and dielectric environment of coinage metal nanoparticles, we have shown an ability to increase the selectivity for a C2+ product (https://doi.org/10.1021/acsami.0c21067) and harvest hot holes (harder to do) as well as hot electrons in plasmonic heterojunctions (https://doi.org/10.1021/acsami.1c10698). Our work on tuning the reaction pathway in high rate CO2 photoreduction was published in 2020 in the high impact journal Applied Catalysis B: Environmental (https://doi.org/10.1016/j.apcatb.2020.118644) and has been cited 55 times to date. We have also shown a way to decrease dependence on noble metals for plasmonics by highlighting hot carrier-driven photochemistry in transition metal nitrides (https://doi.org/10.3390/catal11111374).

(iii) Metal oxides: We started the FES project with TiO2, an old workhorse of solar energy research which is limited by its large electronic bandgap of 3.0-3.2 eV. Recently, we have moved on to multi-element quinary and senary perovskite oxides with bandgaps as low as 1.5 eV (https://doi.org/10.1088/1361-6528/abedec). The concept of oxide perovskites is being pursued collaboratively with the University of Calgary and machine learning based methods are being used to find optimal compositions.

(iv) Halide perovskites: CsPbBr3 nanocrystals coated with a protective layer of carbon nitride gave us high performance in both photoelectrochemical water splitting and CO2 photoreduction. This work was disseminated in a 2022 article in Applied Surface Science (https://doi.org/10.1016/j.apsusc.2022.153276).

We have a wide network of local and international research collaborators. We are now seeking to partner with Canadian SMEs to increase the technology readiness level of our catalysts. It is noteworthy that three of our four platform material systems namely carbon nitrides, transition metal oxides and transition metal nitrides are made of earth-abundant elements, are photochemically stable, are relatively inexpensive to manufacture and lend themselves to "scale up".

Project Files

2024 Graduate Student Teaching Award

Harshitha Rajashekhar

Award

Artificial Photosynthesis Using Semiconductor Nanomaterials

Status

Theme

Principal Investigator

Co-Investigator

Graduate students, Post-Doctoral Fellows, and Highly Qualified Personnel

Faculties

Project Files

T12 P02 Poster 2 2017 Open House

T12 P02 Poster 1 2017 Open House

T12 P02 KumarP Poster 2018 Symposium

T12 P02 ZengS Poster 2018 Symposium

2024 Graduate Student Teaching Award

Alberta Graduate Excellence Scholarship

Alberta Graduate Excellence Scholarship

Alberta Graduate Excellence Scholarship

Alberta Innovates Graduate Student Scholarship

Alberta Innovates Graduate Student Scholarship

Best Poster Award (Symposium N)

CSC'2022 Travel Award

Canada Graduate Scholarships - Doctoral Award

Canada Graduate Scholarships - Doctoral Award

Doctoral Prize of Distinction

Doctoral Recruiting Scholarship

Doctoral Recruiting Scholarship

Doctoral Recruitment Scholarship

Faculty of Engineering Dean's Research Award (DRA)

Gerald J. Maier/NOVA Chemicals Corporation Graduate Recruitment Award

Graduate Recruitment Scholarship

Graduate Scholarship

Graduate Student Scholarship

MITACS Globalink

MITACS Globalink Research Award

MITACS Globalink Research Award

NSERC Scholarship Supplementary Award

Nano-Micro Letters Best Student Paper Award

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

Undergraduate Student Research Award (USRA)

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

A Rational Design of Cu2O-SnO2 Core-Shell Catalyst for Highly Selective CO2-to-CO Conversion

A Review on Photocatalytic CO2 Reduction using Perovskite Oxide Nanomaterials

ATUMS Visiting PhD Student

ATUMS Visiting PhD Student

ATUMS Visiting PhD student

ATUMS visiting PhD student

Active Learning for Optimum Experimental Design - Insight into Perovskite Oxides

Advanced Functional Nanomaterials for Energy and Environmental Applications

Air- and water-stable halide perovskite nanocrystals protected with nearly-monolayer carbon nitride for CO 2 photoreduction and water splitting

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

An Ultrasensitive Fluorescent Paper Based Acidic Gas Sensing Platform

An Ultrasensitive Fluorescent Paper Based Acidic Gas Sensing Platform

Anodic Fabrication of n- and p-type Metal Oxide Nanostructures on Non-Native Substrates

Application of Machine Learning and Computer Vision in Obtaining the Optical Response of Plasmonic Heterostructures

Application of One Dimensional Metal Oxides as Electron transport layer for High Efficiency Halide Perovskite Solar Cells (HPSCs)

Application of TiO2 Nanotubes and Nanowires in Photocatalytic CO2 Reduction

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

Artificial Neural Network-Based Prediction of the Optical Properties of Spherical Core\textendash Shell Plasmonic Metastructures

Asymmetric Multipole Plasmon-Mediated Catalysis Shifts the Product Selectivity of CO 2 Photoreduction toward C2+ Products

Atomistic insights on Halide Composition in Mixed Halide Perovskite Systems: 207Pb solid-state NMR perspective

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

C3N4 and C3N5 Nanosheets As Passivation Layers and Carrier Extractors for Inorganic Semiconductor Nanowires and Quantum Dots

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

CO2 Photoreduction Activity Enhancement and Unexpected Observation of Carbon Monoxide Adsorbates on the Surface of TiO2 Nanotube Arrays Synthesized in Formamide Electrolytes

CO2 photoreduction using earth abundant transition metal oxides & chalcogenides

CO2 reduction performance of TiO2 nanotube-based heterojunction photocatalysts

CVD grown nitrogen doped graphene is an exceptional visible-light driven photocatalyst for surface catalytic reactions

Cathodically Inserted, Widely Dispersed Sr2+ Surface Dopants Produce a Threefold Improvement in the CO2 Photoreduction Activity of TiO2 Nanotube Arrays

Cellulose nanocrystals conjugated with metallophthalocyanines: Applications in visible-light driven photocatalysts and memory devices

Chalcogenide Semiconductor Nanomaterials for Photocatalytic Applications

Characterization of Carrier Dynamics in Metal Oxide Nanostructures and Tellurophenes

Characterization of morphology-dependent transport in lead-halide perovskite printed films using time-resolved terahertz spectroscopy

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

Charge-accumulation-induced mixed photocorrosion in the Z-scheme PEC system