Publications de Michael Graetzel

Publications associées (1 218)

Anisotropic photocatalytic properties of hematite

Hematite is a semiconducting mineral with a role in natural photoelectrochemical processes, and has been studied from the viewpoint of solar energy utilization. Hematite is an anisotropic conductor, with faster conduction parallel to (001) planes. Flatband ...

2009

Recent Advances in Sensitized Mesoscopic Solar Cells

Michael Graetzel

Perhaps the largest challenge for our global society is to find ways to replace the slowly but inevitably vanishing fossil fuel supplies by renewable resources and, at the same time, avoid negative effects from the current energy system on climate, environ ...

American Chemical Society2009

Evolution of an Oxygen Near-Edge X-ray Absorption Fine Structure Transition in the Upper Hubbard Band in alpha-Fe2O3 upon Electrochemical Oxidation

Michael Graetzel, Kevin Sivula

Electrochemical oxidation of hematite (alpha-Fe2O3) nanoparticulate films at 600 mV vs Ag+/AgCl in KOH electrolyte forms a species at the hematite surface which causes a new transition in the upper Hubbard band between the Fe(3d)-O(2p) state region and the ...

American Chemical Society2011

Sequential catalysis enables enhanced C-C coupling towards multi-carbon alkenes and alcohols in carbon dioxide reduction: a study on bifunctional Cu/Au electrocatalysts

Michael Graetzel, Shaik Mohammed Zakeeruddin, Dan Ren, Jing Gao

Electrochemical reduction of carbon dioxide (CO2) to multi-carbon products such as ethylene, ethanol and n-propanol offers a promising path for utilization of excessive CO2 and energy storage. Oxide-derived Cu electrodes are among the best electrocatalysts ...

ROYAL SOC CHEMISTRY2019

Facile and low-cost synthesis of a novel dopant-free hole transporting material that rivals Spiro-OMeTAD for high efficiency perovskite solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin

A Spiro fluorene-based dopant-free hole-transporting material denoted as Spiro-IA has been designed and developed from inexpensive starting materials with high yield via a simple synthetic approach for application in perovskite solar cells (PSCs). The unit ...

ROYAL SOC CHEMISTRY2021

Dynamic Nuclear Polarization Enables NMR of Surface Passivating Agents on Hybrid Perovskite Thin Films

Michael Graetzel, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Lukas Pfeifer, Aditya Mishra, Michael Allan Hope, Masaud Hassan S Almalki

Surface and bulk molecular modulators are the key to improving the efficiency and stability of hybrid perovskite solar cells. However, due to their low concentration, heterogeneous environments, and low sample mass, it remains challenging to characterize t ...

2022

Multihole water oxidation catalysis on haematite photoanodes revealed by operando spectroelectrochemistry and DFT

Michael Graetzel, Matthew Thomas Mayer

Water oxidation is the key kinetic bottleneck of photoelectrochemical devices for fuel synthesis. Despite advances in the identification of intermediates, elucidating the catalytic mechanism of this multi-redox reaction on metal-oxide photoanodes remains a ...

NATURE PUBLISHING GROUP2020

Solution-based heteroepitaxial growth of stable mixed cation/anion hybrid perovskite thin film under ambient condition via a scalable crystal engineering approach

Michael Graetzel, Shaik Mohammed Zakeeruddin, Fabrizio Giordano

The performance of perovskite solar cells is under direct control of the perovskite film quality and controlling the crystalinity and orientation of solution-processed perovskite film is a fundamental challenge. In this study, we present a scalable fabrica ...

Elsevier2020

Activation Energies for the Rate-Limiting Step in Water Photooxidation by Nanostructured alpha-Fe2O3 and TiO2

Michael Graetzel, Kevin Sivula

Competition between charge recombination and the forward reactions required for water splitting limits the efficiency of metal-oxide photocatalysts. A key requirement for the photochemical oxidation of water on both nanostructured alpha-Fe2O3 and TiO2 is t ...

2011

Silica-copper catalyst interfaces enable carbon-carbon coupling towards ethylene electrosynthesis

Michael Graetzel, Dan Ren, Yelin Hu, Jun Li, Reza Zamani

Membrane electrode assembly (MEA) electrolyzers offer a means to scale up CO2-to-ethylene electroconversion using renewable electricity and close the anthropogenic carbon cycle. To date, excessive CO2 coverage at the catalyst surface with limited active si ...

Nature Research2021

Multi-Length Scale Structure of 2D/3D Dion-Jacobson Hybrid Perovskites Based on an Aromatic Diammonium Spacer

Michael Graetzel, David Lyndon Emsley, Dominik Józef Kubicki, Thomas La Grange, Jovana Milic, Aditya Mishra, Amita Ummadisingu, Algirdas Ducinskas

Dion-Jacobson (DJ) iodoplumbates based on 1,4-phenylenedimethanammonium (PDMA) have recently emerged as promising light absorbers for perovskite solar cells. While PDMA is one of the simplest aromatic spacers potentially capable of forming a DJ structure b ...

2021

Effect of bulky groups in ruthenium heteroleptic sensitizers on dye sensitized solar cell performance

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

Two novel heteroleptic ruthenium sensitizers, TT204 and TT205, containing bulky substituents at the 4,4-positions of the ancillary 2,2-bipyridine ligand, were synthesized and characterized. They exhibit absorption maxima in the visible region at 520-530 nm ...

2012

Suppressing recombination in perovskite solar cells via surface engineering of TiO2 ETL

Michael Graetzel, Shaik Mohammed Zakeeruddin, Daniel Prochowicz

Hybrid perovskite solar cells (PSCs) have gained significant attention owing to their excellent physicochemical and photovoltaic properties. PSCs typically consist of a perovskite light absorber sandwiched between two carrier selective layers optimized wit ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Fabrication and performance of a monolithic dye-sensitized TiO2/Cu(In,Ga)Se2 thin film tandem solar cell

Michael Graetzel, Sophie Wenger

Tandem solar cells using different bandgap absorbers allow efﬁcient photovoltaic conversion in a wide range of the solar spectrum. The optical gaps of the dye-sensitized solar cell and the Cu(In,Ga)Se2 solar cell are ideal for application in double-junctio ...

AIP American Institute of Physics2009

Hydroxamic acid pre-adsorption raises the efficiency of cosensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Felix Thomas Eickemeyer, Yiming Cao, Jiajia Suo, Yameng Ren, Dan Zhang

Dye-sensitized solar cells (DSCs) convert light into electricity by using photosensitizers adsorbed on the surface of nanocrystalline mesoporous titanium dioxide (TiO2) films along with electrolytes or solid charge-transport materials(1-3). They possess ma ...

NATURE PORTFOLIO2023

Analysing the effect of crystal size and structure in highly efficient CH3NH3PbI3 perovskite solar cells by spatially resolved photo- and electroluminescence imaging

Michael Graetzel, Jeong-Hyeok Im

CH3NH3PbI3 perovskite solar cells with a mesoporous TiO2 layer and spiro-MeOTAD as a hole transport layer (HTL) with three different CH3NH3I concentrations (0.032 M, 0.044 M and 0.063 M) were investigated. Strong variations in crystal size and morphology r ...

Royal Society of Chemistry2015

Photoelectrochemical Water Splitting with Mesoporous Hematite Prepared by a Solution-Based Colloidal Approach

Michael Graetzel, Kevin Sivula, Florian Le Formal

Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe2O3) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostruc ...

American Chemical Society2010

Ti-1-graphene single-atom material for improved energy level alignment in perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Felix Thomas Eickemeyer, Zaiwei Wang, Hongwei Zhu

Carbon-based perovskite solar cells (C-PSCs) are widely accepted as stable, cost-effective photovoltaics. However, C-PSCs have been suffering from relatively low power conversion efficiencies (PCEs) due to severe electrode-related energy loss. Herein, we r ...

2021

Absorption Spectra and Excited State Energy Levels of the N719 Dye on TiO2 in Dye-Sensitized Solar Cell Models

Michael Graetzel, Mohammad Khaja Nazeeruddin

We have investigated the absorption spectrum and the alignment of ground and excited state energies for the prototypical N719 Ru(II) sensitizer adsorbed on an extended TiO2 model by means of high level DFT/TDDFT calculations. The calculated and experimenta ...

American Chemical Society2011

Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mingkui Wang, Péter Kalman Péchy

We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of din ...

2009