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Dan Ren

Cette personne n’est plus à l’EPFL

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Publications associées (43)

Benzylammonium‐Mediated Formamidinium Lead Iodide Perovskite Phase Stabilization for Photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Dominik Józef Kubicki, David Lyndon Emsley, Zaiwei Wang, Anwar Qasem M Alanazi, Jovana Milic, Dan Ren, Masaud Hassan S Almalki, Aditya Mishra, Felix Thomas Eickemeyer, Hong Zhang

There is an ongoing surge of interest in the use of formamidinium (FA) lead iodide perovskites in photovoltaics due to their exceptional optoelectronic properties. However, thermodynamic instability of the desired cubic perovskite (α-FAPbI3) phase at ambie ...

2021

Multimodal host–guest complexation for efficient and stable perovskite photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Marko Mladenovic, David Lyndon Emsley, Farzaneh Jahanbakhshi, Paramvir Ahlawat, Zaiwei Wang, Jovana Milic, Dan Ren, Aditya Mishra, Felix Thomas Eickemeyer, Hong Zhang, Zhaowen Dong, Jinming Guo, Michael Allan Hope, Anurag Krishna, Olivier Ouellette, Tzu-Sen Su, Zhiwen Zhou

Formamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host–guest complexation strat ...

Nature Research2021

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

Michael Graetzel, Yelin Hu, Reza Zamani, Xiaoyan Wang, Dan Ren, Jun Li, Ziyun Wang, Yi Xu

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

Spectroelectrochemical and Chemical Evidence of Surface Passivation at Zinc Ferrite (ZnFe 2 O 4 ) Photoanodes for Solar Water Oxidation

Michael Graetzel, Mounir Driss Mensi, Kevin Sivula, Nestor Guijarro Carratala, Liang Yao, Yongpeng Liu, Dan Ren, Meng Xia

Recent advances in low‐cost manufacturing as well as in bulk/interface engineering have positioned zinc ferrite (ZnFe2O4, ZFO) in the spotlight as a candidate material for solar water oxidation. However, the severe recombination at the reactive interface r ...

2021

Gold-in-copper at low *CO coverage enables efficient electromethanation of CO2

Michael Graetzel, Pengfei Ou, Xiaoyan Wang, Dan Ren, Yang Li, Jun Li, Ziyun Wang, Yongfeng Xie, Yi Xu, Yiping Wang

The renewable-electricity-powered CO2 electroreduction reaction provides a promising means to store intermittent renewable energy in the form of valuable chemicals and dispatchable fuels. Renewable methane produced using CO2 electroreduction attracts inter ...

Nature Research2021

New Insights into the Interface of Electrochemical Flow Cells for Carbon Dioxide Reduction to Ethylene

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

The implementation of an electrochemical flow cell has enabled improved efficiency for CO2 reduction. However, in situ spectroscopic insights into the interface are still lacking. Here, we investigate a series of copper layers with different thicknesses on ...

AMER CHEMICAL SOC2021

Micro-Electrode with Fast Mass Transport for Enhancing Selectivity of Carbonaceous Products in Electrochemical CO2 Reduction

Michael Graetzel, Mingkui Wang, Jingshan Luo, Xiaoyu Zhang, Dan Ren, Qixing Zhang

During electrochemical carbon dioxide (CO2) reduction on copper electrodes in an aqueous electrolyte, one of the key challenges is the competition between hydrogen evolution and CO2 reduction, especially under large current density. Here, micro-electrodes ...

2021

A hybrid bulk-heterojunction photoanode for direct solar-to-chemical conversion dagger

Michael Graetzel, Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Barbara Alexandra Primera Darwich, Yongpeng Liu, Rebekah Anne Wells, Dan Ren, Han-Hee Cho, Meng Xia

Organic semiconductors (OSs) are emerging candidates as light-harvesting materials in photoelectrochemical (PEC) cells for direct solar-to-chemical conversion. Despite significant recent progress with OS-based photocathodes, the development of efficient an ...

ROYAL SOC CHEMISTRY2021

Carbazol-phenyl-phenothiazine-based sensitizers for dye-sensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Yi Ding, Wei Huang, Dan Ren, Felix Thomas Eickemeyer, Zhongjin Shen, Yunfei Jiao, Lukas Pfeifer

Heteroaromatic units are commonly used as pi-spacers for sensitizers in dye-sensitized solar cells (DSSCs). Here, we investigated the influence of the pi-spacer on the photophysical properties, electrochemical properties and photovoltaic performance of car ...

Royal Society of Chemistry2021

Combined Precursor Engineering and Grain Anchoring Leading to MA-Free, Phase-Pure, and Stable alpha-Formamidinium Lead Iodide Perovskites for Efficient Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Carole Graetzel, Linfeng Pan, Yuhang Liu, Dan Ren, Jing Gao, Hongwei Zhu, Anurag Krishna, Olivier Ouellette

alpha-Formamidinium lead iodide (alpha-FAPbI(3)) is one of the most promising candidate materials for high-efficiency and thermally stable perovskite solar cells (PSCs) owing to its outstanding optoelectrical properties and high thermal stability. However, ...

Wiley-VCH Verlag GmbH2021

Crown Ether Modulation Enables over 23% Efficient Formamidinium-Based Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mounir Driss Mensi, Ursula Röthlisberger, Ulf Anders Hagfeldt, Jun Ho Yum, Kevin Sivula, Marko Mladenovic, David Lyndon Emsley, Farzaneh Jahanbakhshi, Jovana Milic, Dan Ren, Aditya Mishra, Felix Thomas Eickemeyer, Hong Zhang, Michael Allan Hope, Jun Li, Anurag Krishna, Olivier Ouellette, Zhiwen Zhou

The use of molecular modulators to reduce the defect density at the surface and grain boundaries of perovskite materials has been demonstrated to be an effective approach to enhance the photovoltaic performance and device stability of perovskite solar cell ...

2020

Cu2O photocathodes with band-tail states assisted hole transport for standalone solar water splitting

Michael Graetzel, Ulf Anders Hagfeldt, Kevin Sivula, Linfeng Pan, Liang Yao, Yuhang Liu, Dan Ren

Photoelectrochemical water splitting provides a promising solution for harvesting and storing solar energy. As the best-performing oxide photocathode, the Cu2O photocathode holds the performance rivaling that of many photovoltaic semiconductor-based photoc ...

Nature Research2020

Tailored Amphiphilic Molecular Mitigators for Stable Perovskite Solar Cells with 23.5% Efficiency

Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Mohammad Ibrahim Dar, Xiong Li, Xiaofei Dong, Linfeng Pan, Zaiwei Wang, Yuhang Liu, Brian Irving Carlsen, Dan Ren, Marco Alejandro Ruiz Preciado, Bowen Yang, Felix Thomas Eickemeyer, Hongwei Zhu, Shilong Wang

Passivation of interfacial defects serves as an effective means to realize highly efficient and stable perovskite solar cells (PSCs). However, most molecular modulators currently used to mitigate such defects form poorly conductive aggregates at the perovs ...

Wiley2020

Guanine‐Stabilized Formamidinium Lead Iodide Perovskites

Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Amita Ummadisingu, Marko Mladenovic, Dominik Józef Kubicki, David Lyndon Emsley, Linfeng Pan, Paramvir Ahlawat, Yuhang Liu, Jovana Milic, Dan Ren, Li Hong, Marco Alejandro Ruiz Preciado

Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α‐FAPbI3 phase to the thermodynamically stable yet photovoltaically inactive δ‐FAPbI3 ph ...

2020

Photoelectrocatalytic arene C–H amination

Xile Hu, Laurent Liardet, Jingshan Luo, Lei Zhang, Dan Ren

Photoelectrochemical cells are widely studied for solar energy conversion. However, they have rarely been used for the synthesis of high added-value organic molecules. Here we describe a strategy to use haematite, an abundant and robust photoanode, for non ...

2019

Atomic-Level Microstructure of Efficient Formamidinium-Based Perovskite Solar Cells Stabilized by 5-Ammonium Valeric Acid Iodide Revealed by Multinuclear and Two-Dimensional Solid-State NMR

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Marine Eva Fedora Bouduban, Marko Mladenovic, Fabrizio Giordano, Dominik Józef Kubicki, David Lyndon Emsley, Farzaneh Jahanbakhshi, Essa Awadh R Alharbi, Daniel Prochowicz, Anwar Qasem M Alanazi, Jovana Milic, Dan Ren

Chemical doping of inorganic–organic hybrid perovskites is an effective way of improving the performance and operational stability of perovskite solar cells (PSCs). Here we use 5-ammonium valeric acid iodide (AVAI) to chemically stabilize the structure of ...

2019

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

SnS Quantum Dots as Hole Transporter of Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Xiaofei Dong, Peng Wang, Zaiwei Wang, Yuhang Liu, Yang Li, Dan Ren, Yang Li

Perovskite solar cells have achieved comparable power conversion efficiencies as commercial silicon cells, making the issue of long-term operation stability as the most critical scientific factor toward industrial realization. In this work, we introduce Sn ...

AMER CHEMICAL SOC2019

Selective C-C Coupling in Carbon Dioxide Electroreduction via Efficient Spillover of Intermediates As Supported by Operando Raman Spectroscopy

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jingshan Luo, Dan Ren, Jing Gao, Hong Zhang

Developing efficient systems for the conversion of carbon dioxide to valuable chemicals using solar power is critical for mitigating climate change and ascertaining the worlds future supply of clean fuels. Here, we introduce a mesoscopic cathode consisting ...

AMER CHEMICAL SOC2019

Bimetallic Electrocatalysts for Carbon Dioxide Reduction

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

Electrochemical reduction of carbon dioxide, using the electricity generated from renewable energy sources, has the potential of rendering a carbon-neutral energy economy. Developing selective, efficient and robust electrocatalysts is the key step towards ...

SWISS CHEMICAL SOC2019

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