skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Artificial inflation of apparent photocatalytic activity induced by catalyst-mass-normalization and a method to fairly compare heterojunction systems

Journal Article · · Energy & Environmental Science
DOI:https://doi.org/10.1039/C9EE00452A· OSTI ID:1559531

Despite the possibility of using photocatalysts to sustainably produce fuels and chemicals, overall reaction rates remain prohibitively low, largely limited by recombination of photogenerated electrons and holes. Past research on suppressing this recombination by the addition of co-catalysts or by the formation of heterojunctions has led to claims that rates show enhancement compared to the single-component, junction-free counterparts. Yet, comparing these systems is rendered difficult by the common practice of reporting rates on a catalyst mass basis. Using a model system of TiO2 and g-C3N4 with Pt, here we show that normalizing photocatalytic rates by mass fails to provide mechanistic insight and can also artificially inflate the apparent performance of heterojunction systems—in our case, overestimating the enhancement by 24 ± 7%. This effect is caused by the nonlinearity of light absorption with respect to the concentration of each light-absorbing component, according to Beer's law. This factor needs to be taken into account to verify if improvements in absolute activity correspond to intrinsic activity. To this end, an approach is introduced for approximating a system quantum yield from measured reaction rates under simulated solar or otherwise polychromatic light. A sensitivity analysis provides guidelines for reducing the artificial enhancement introduced by mass-normalization for any heterojunction system.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC); Stanford Graduate Fellowship; National Science Foundation (NSF); Stanford University
Grant/Contract Number:
AC02-06CH11357; ECCS-1542152
OSTI ID:
1559531
Alternate ID(s):
OSTI ID: 1508664
Journal Information:
Energy & Environmental Science, Vol. 12, Issue 5; ISSN 1754-5692
Publisher:
Royal Society of ChemistryCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 19 works
Citation information provided by
Web of Science

References (51)

Simple pyrolysis of urea into graphitic carbon nitride with recyclable adsorption and photocatalytic activity journal January 2011
Making MetalCarbon Nitride Heterojunctions for Improved Photocatalytic Hydrogen Evolution with Visible Light journal June 2010
Photocatalytic and photoelectrocatalytic reduction of CO 2 using heterogeneous catalysts with controlled nanostructures journal January 2016
Powering the planet: Chemical challenges in solar energy utilization journal October 2006
A general framework for the assessment of solar fuel technologies journal January 2015
Hot-Electron Transfer from Semiconductor Nanocrystals journal June 2010
Engineering titania nanostructure to tune and improve its photocatalytic activity journal March 2016
Perovskite Solar Cells: From the Laboratory to the Assembly Line journal December 2017
In situ nitrogen-doped hollow-TiO 2 /g-C 3 N 4 composite photocatalysts with efficient charge separation boosting water reduction under visible light journal January 2017
Semiconductor heterojunction photocatalysts: design, construction, and photocatalytic performances journal January 2014
Review on Modified TiO 2 Photocatalysis under UV/Visible Light: Selected Results and Related Mechanisms on Interfacial Charge Carrier Transfer Dynamics journal November 2011
Highly Efficient Visible-Light-Induced Photoactivity of Z-Scheme g-C 3 N 4 /Ag/MoS 2 Ternary Photocatalysts for Organic Pollutant Degradation and Production of Hydrogen journal December 2016
Polymeric Graphitic Carbon Nitride for Heterogeneous Photocatalysis journal July 2012
Materials for solar fuels and chemicals journal December 2016
Graphitic carbon nitride (g-C3N4)–Pt-TiO2 nanocomposite as an efficient photocatalyst for hydrogen production under visible light irradiation journal January 2012
Structural Investigation of Graphitic Carbon Nitride via XRD and Neutron Diffraction journal March 2015
A Generalized Ligand-Exchange Strategy Enabling Sequential Surface Functionalization of Colloidal Nanocrystals journal February 2011
Heterojunctions in g-C3N4/B-TiO2 nanosheets with exposed {001} plane and enhanced visible-light photocatalytic activities journal May 2016
High-yield synthesis and optical properties of g-C 3 N 4 journal January 2015
Nonhydrolytic Synthesis of High-Quality Anisotropically Shaped Brookite TiO2 Nanocrystals
  • Buonsanti, Raffaella; Grillo, Vincenzo; Carlino, Elvio
  • Journal of the American Chemical Society, Vol. 130, Issue 33, p. 11223-11233 https://doi.org/10.1021/ja803559b
journal August 2008
Artificial photosynthesis for solar water-splitting journal July 2012
Mechanism of Photocatalytic Water Splitting in TiO 2 . Reaction of Water with Photoholes, Importance of Charge Carrier Dynamics, and Evidence for Four-Hole Chemistry journal October 2008
A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production journal April 2007
Exfoliated Graphitic Carbon Nitride Nanosheets as Efficient Catalysts for Hydrogen Evolution Under Visible Light journal March 2013
Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30% journal October 2016
Plastic waste as a feedstock for solar-driven H 2 generation journal January 2018
Dissolution and Liquid Crystals Phase of 2D Polymeric Carbon Nitride journal February 2015
Best Practice in Photocatalysis: Comparing Rates or Apparent Quantum Yields? journal May 2015
The preparation, and applications of g-C3N4/TiO2 heterojunction catalysts—a review journal October 2016
Graphitic carbon nitride materials: variation of structure and morphology and their use as metal-free catalysts journal January 2008
Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: A review of fundamentals, progress and problems journal March 2008
Mesoporous TiO 2 /g-C 3 N 4 Microspheres with Enhanced Visible-Light Photocatalytic Activity journal September 2017
A photochemical diode artificial photosynthesis system for unassisted high efficiency overall pure water splitting journal April 2018
A review of TiO 2 nanostructured catalysts for sustainable H 2 generation journal March 2017
Understanding TiO 2 Photocatalysis: Mechanisms and Materials journal May 2014
Synthesis and efficient visible light photocatalytic H2 evolution of a metal-free g-C3N4/graphene quantum dots hybrid photocatalyst journal September 2016
Fabrication of TiO 2 -doped single layer graphitic-C 3 N 4 and its visible-light photocatalytic activity journal October 2017
Size Matters: Cocatalyst Size Effect on Charge Transfer and Photocatalytic Activity journal December 2017
Cover Picture: A Metallaanthracene and Derived Metallaanthraquinone (Angew. Chem. Int. Ed. 1/2017) journal November 2016
A solar-charged photoelectrochemical wastewater fuel cell for efficient and sustainable hydrogen production journal January 2017
Direct observation of electron dynamics in the attosecond domain journal July 2005
Effect of contact interface between TiO2 and g-C3N4 on the photoreactivity of g-C3N4/TiO2 photocatalyst: (0 0 1) vs (1 0 1) facets of TiO2 journal March 2015
Facile in situ synthesis of plasmonic nanoparticles-decorated g-C 3 N 4 /TiO 2 heterojunction nanofibers and comparison study of their photosynergistic effects for efficient photocatalytic H 2 evolution journal January 2016
A review on g-C 3 N 4 -based photocatalysts journal January 2017
Photocatalytic H2 and Added-Value By-Products - The Role of Metal Oxide Systems in Their Synthesis from Oxygenates journal September 2011
Trap states and carrier dynamics of TiO2 studied by photoluminescence spectroscopy under weak excitation condition journal January 2010
Facile Soft-Templated Synthesis of High-Surface Area and Highly Porous Carbon Nitrides journal February 2017
The future of solar fuels: when could they become competitive? journal January 2018
TiO 2 Photocatalysis: A Historical Overview and Future Prospects journal December 2005
Excitation Energy Dependence of the Photoluminescence Quantum Yields of Core and Core/Shell Quantum Dots journal June 2013
Plastic waste as a feedstock for solar-driven H2 generation text January 2018

Cited By (1)

Solar thermal desalination as a nonlinear optical process journal June 2019