Publications de Yongpeng Liu | EPFL Graph Search

Assessing the Charge Carrier Dynamics at Hybrid Interfaces of Organic Photoanodes for Solar Fuels

Kevin Sivula, Yongpeng Liu, Han-Hee Cho, Alexander Wieczorek

Organic semiconductors (OSCs) have emerged as promising active layers for photoanodes to drive photoelectrochemical (PEC) oxidation reactions. Interfacing an OSC with an inorganic electron transport layer (ETL) is key to enabling both high performance and ...

Amer Chemical Soc2024

Understanding and Mitigating the Degradation of Perovskite Solar Cells Based on a Nickel Oxide Hole Transport Material during Damp Heat Testing

Christophe Ballif, Mounir Driss Mensi, Jun Ho Yum, Kevin Sivula, Yongpeng Liu, Marion Solange Madeleine Dussouillez, Christian Michael Wolff

The development of stable materials, processable on alarge area,is a prerequisite for perovskite industrialization. Beyond the perovskiteabsorber itself, this should also guide the development of all otherlayers in the solar cell. In this regard, the use o ...

AMER CHEMICAL SOC2023

Efficient Cu2O Photocathodes for Aqueous Photoelectrochemical CO2 Reduction to Formate and Syngas

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mounir Driss Mensi, Kevin Sivula, Linfeng Pan, Yongpeng Liu, Dan Ren, Jing Gao, Meng Xia, Jun Li

Photoelectrochemical carbon dioxide reduction (PEC-CO2R) represents a promising approach for producing renewable fuels and chemicals using solar energy. However, attaining even modest solar-to-fuel (STF) conversion efficiency often necessitates the use of ...

Amer Chemical Soc2023

Photoelectrochemical CO2 Reduction at a Direct CuInGaS2/Electrolyte Junction

Michael Graetzel, Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu, Simon Nussbaum, Dan Ren, Meng Xia

Photoelectrochemical (PEC) CO2 reduction has received considerable attention given the inherent sustainability and simplicity of directly converting solar energy into carbonbased chemical fuels. However, complex photocathode architectures with protecting l ...

AMER CHEMICAL SOC2023

Covalent Organic Framework Nanoplates Enable Solution-Processed Crystalline Nanofilms for Photoelectrochemical Hydrogen Evolution

Michael Graetzel, Kevin Sivula, Yongpeng Liu, Meng Xia

As covalent organic frameworks (COFs) are coming of age, the lack of effective approaches to achieve crystalline and centimeter-scale-homogeneous COF films remains a significant bottleneck toward advancing the application of COFs in optoelectronic devices. ...

AMER CHEMICAL SOC2022

Bulk Heterojunction Organic Semiconductor Photoanodes: Tuning Energy Levels to Optimize Electron Injection

Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Barbara Alexandra Primera Darwich, Yongpeng Liu, Han-Hee Cho, Juan Manuel Moreno Naranjo

The use of a bulk heterojunction of organic semiconductors to drive photoelectrochemical water splitting is an emerging trend; however, the optimum energy levels of the donor and acceptor have not been established for photoanode operation with respect to e ...

AMER CHEMICAL SOC2022

Photodehydrogenation of Ethanol over Cu2O/TiO2 Heterostructures

Yongpeng Liu

The photodehydrogenation of ethanol is a sustainable and potentially cost-effective strategy to produce hydrogen and acetaldehyde from renewable resources. The optimization of this process requires the use of highly active, stable and selective photocataly ...

2021

Key factors boosting the performance of planar ZnFe2O4 photoanodes for solar water oxidation

Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu, Florent Alexandre Boudoire

The performance of ZnFe2O4 photoanodes largely depends on their nanostructure, crystallinity and n-type doping, though decoupling their impact on photoactivity remains a challenge. Herein, the combined effects of the synthesis temperature and reductive ann ...

Royal Society of Chemistry2021

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

A semiconducting polymer bulk heterojunction photoanode for solar water oxidation

Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Yongpeng Liu, Rebekah Anne Wells, Florent Alexandre Boudoire, Han-Hee Cho

Organic semiconductors hold promise to enable scalable, low-cost and high-performance artificial photosynthesis. However, the performance of systems based on organic semiconductors for light-driven water oxidation have remained poor compared with inorganic ...

NATURE RESEARCH2021

Spray Synthesis of CuFeO2 Photocathodes and In-Operando Assessment of Charge Carrier Recombination

Kevin Sivula, Florian Le Formal, Nestor Guijarro Carratala, Yongpeng Liu, Florent Alexandre Boudoire, Charles Roger Jean Lhermitte

Semiconducting delafossite-phase CuFeO2 is a promising photocathode material for solar-driven hydrogen production given its suitable energy levels and established robustness for photoelectrochemical water reduction. Nevertheless, reported methods for prepa ...

AMER CHEMICAL SOC2021

Identifying Reactive Sites and Surface Traps in Chalcopyrite Photocathodes

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

Gathering information on the atomic nature of reactive sites and trap states is key to fine tuning catalysis and suppressing deleterious surface voltage losses in photoelectrochemical technologies. Here, spectroelectrochemical and computational methods wer ...

Wiley-VCH Verlag GmbH2021

A Direct Z-Scheme for the Photocatalytic Hydrogen Production from a Water Ethanol Mixture on CoTiO3/TiO2 Heterostructures

Kevin Sivula, Nestor Guijarro Carratala, Liang Yao, Yongpeng Liu

Photocatalytic H-2 evolution from ethanol dehydrogenation is a convenient strategy to store solar energy in a highly valuable fuel with potential zero net CO2 balance. Herein, we report on the synthesis of CoTiO3/TiO2 composite catalysts with controlled am ...

AMER CHEMICAL SOC2021

Defect engineered nanostructured LaFeO3 photoanodes for improved activity in solar water oxidation

Mounir Driss Mensi, Kevin Sivula, Xavier Pereira Da Costa, Nestor Guijarro Carratala, Liang Yao, Yongpeng Liu

LaFeO3 (LFO) is recognized as a candidate material for solar water oxidation, but its photoelectrochemical response remains modest and stagnant. With the aim of advancing LFO photoanodes for the oxygen evolution reaction (OER), here, a nanorod array-type e ...

Royal Society of Chemistry2021

Novel Interfacial Characterization and Surface Engineering in Semiconductor Electrodes for Optimized Solar Fuel Production

Yongpeng Liu

Harvesting sunlight, the ultimate renewable power source, in a cost-effective way has been long recognized as a necessary route to meet the global energy challenges. Solar energy can be transformed into electricity by means of photovoltaic devices to suppl ...

EPFL2021

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

Establishing Stability in Organic Semiconductor Photocathodes for Solar Hydrogen Production

Jun Ho Yum, Kevin Sivula, Florian Le Formal, Muhammad Aiman Bin Rahmanudin Hamdan, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Yongpeng Liu, Rebekah Anne Wells, Florent Alexandre Boudoire, Han-Hee Cho

As organic semiconductors attract increasing attention to application in the fields of bioelectronics and artificial photosynthesis, understanding the factors that determine their robust operation in direct contact with aqueous electrolytes becomes a criti ...

AMER CHEMICAL SOC2020

Understanding Surface Recombination Processes Using Intensity-Modulated Photovoltage Spectroscopy on Hematite Photoanodes for Solar Water Splitting

Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu

Converting solar energy into hydrogen through photoelectrochemical (PEC) water splitting offers a promising route towards a fully renewable energy economy. A fundamental understanding of photogenerated charge recombination processes in semiconducting photo ...

WILEY-V C H VERLAG GMBH2020

MIL-101(Fe)/g-C3N4 for enhanced visible-light-driven photocatalysis toward simultaneous reduction of Cr(VI) and oxidation of bisphenol A in aqueous media

Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu, Feiping Zhao

Heterostructured composites with an excellent photocatalytic activity have attracted increasing attention because of their great application in environmental remediation. Herein, a MIL-101(Fe)/g-C3N4 heterojunction was synthesized via in-situ growth of MIL ...

ELSEVIER2020

Fully Conjugated Donor–Acceptor Block Copolymers for Organic Photovoltaics via Heck–Mizoroki Coupling

Kevin Sivula, Arvindh Sekar, Liang Yao, Yongpeng Liu, Charles Roger Jean Lhermitte, Han-Hee Cho

2019