Zhaofu Fei

Anchoring single platinum atoms onto nickel nanoparticles affords highly selective catalysts for lignin conversion

Lichen Bai, Lu Chen, Paul Joseph Dyson, Zhaofu Fei, Ulf Anders Hagfeldt, Gabor Laurenczy, Jun Li, Linfeng Pan, Yun Tong, Antoine Philippe Van Muyden

Due to the highly complex polyphenolic structure of lignin, depolymerization without a prior chemical treatment is challenging, and new catalysts are required. Atomically dispersed catalysts are able to maximize the atomic efficiency of noble metals, simultaneously providing an alternative strategy to tune the activity and selectivity by alloying with other abundant metal supports. Here, we report a highly active and selective catalyst comprising monodispersed (single) Pt atoms on Ni nanoparticles supported on carbon (denoted as Pt1Ni/C, where Pt-1 represents single Pt atoms), designed for the reductive depolymerization of lignin. Selectivity toward 4-n-propylsyringol and 4-n-propylguaiacol exceeds 90%. The activity and selectivity of the Pt1Ni/C catalyst in the reductive depolymerization of lignin may be attributed to synergistic effects between the Ni nanoparticles and the single Pt atoms.

ELSEVIER2021

Boosting hydrogen production via urea electrolysis on an amorphous nickel phosphide/graphene hybrid structure

Lu Chen, Paul Joseph Dyson, Zhaofu Fei, Yun Tong

Overall urea electrolysis has favorable thermodynamic properties and can complement traditional water splitting by simultaneously purifying urea-rich waste streams. However, the kinetics of the reaction is slow and more efficient catalysts are required. In this work, we describe a facile way to fabricate amorphous nickel phosphides on graphene nanosheets (a-Ni2P/G), which shows high efficient performance for overall urea electrolysis. The a-Ni2P/G catalyst has abundant surface area for abundant catalytic active sites and high proportion of Ni3+ active sites, realizing a superior intrinsic activity for both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). Impressively, the a-Ni2P/G catalyst requires only much lower potentials of 1.28 V and - 0.1 V for UOR and HER at 10 mA cm(-2). The assembled a-Ni2P/G parallel to a-Ni2P/G electrolyzer needs a small cell voltage of 1.39 V to deliver the current density of 10 mA cm(-2). This work highlights a promising pathway to develop a cost-efficient catalyst for energy-saving H-2 generation combined with waste water purification.

SPRINGER2021

Engineering long-term stability into perovskite solar cells via application of a multi-functional TFSI-based ionic liquid

Bin Ding, Paul Joseph Dyson, Farzaneh Fadaei Tirani, Zhaofu Fei, Hiroyuki Kanda, Wen Luo, Mohammad Khaja Nazeeruddin, Rosario Scopelliti, Yi Zhang, Bing Zhang, Andreas Züttel

Organic-inorganic metal-halide perovskite solar cells (PSCs) have achieved a certified power-conversion efficiency (PCE) of 25.5%. However, long-term stability and air stability of the PSCs are still major concerns and hamper commercialization. Herein, we employ a multi-functional ionic liquid (IL), 1,3-bis(cyanomethyl)imidazolium bis(trifluoromethylsulfonyl)imide ([Bcim][TFSI]), which contains an imidazolium cation functionalized with nitrile (CN) groups and the TFSI anion and is, additionally, able to form an extensive network of low-barrier H bonds, as an additive in perovskite-precursor solutions. Because of a combination of the Lewis-basic CN groups and the hydrophobic TFSI anion in the IL, highly crystalline perovskite films with large grain sizes are obtained. The IL-modified perovskite films afford PSCs with long-term stability and PCEs > 21%. The stability of unencapsulated devices retain >95% of their original efficiency after 1,000 h of aging. This study demonstrates the considerable potential of TFSI-based ILs to improve the performance of PSCs.

ELSEVIER2021

Lignin First: Confirming the Role of the Metal Catalyst in Reductive Fractionation

Lu Chen, Xinjiang Cui, Paul Joseph Dyson, Zhaofu Fei, Gabor Laurenczy, Antoine Philippe Van Muyden, Ning Yan

Rhodium nanoparticles embedded on the interior of hollow porous carbon nanospheres, able to sieve monomers from polymers, were used to confirm the precise role of metal catalysts in the reductive catalytic fractionation of lignin. The study provides clear evidence that the primary function of the metal catalyst is to hydrogenate monomeric lignin fragments into more stable forms following a solvent-based fractionation and fragmentation of lignin.

AMER CHEMICAL SOC2021

A polymeric ionic liquid catalyst for the N-formylation and N-methylation of amines using CO2/PhSiH3

Arunraj Chidambaram, Paul Joseph Dyson, Zhaofu Fei, Aswin Gopakumar, Serhii Shyshkanov, Kyriakos Stylianou, Dmitry Vasilyev, Andreas Züttel

We describe a polymeric ionic liquid (PIL) derived from trimethyl(p-vinylbenzyl)ammonium chloride ([VBTAm]Cl) that efficiently catalyzes the N-formylation of amines employing CO2 and PhSiH3 at room temperature with low catalyst loadings in near-quantitative yield. Under more forcing conditions N-methylated products can be selectively obtained. The PIL catalyst can be easily recovered and reused repeatedly without a decrease in activity. The reaction mechanism was studied in situ using high-pressure NMR spectroscopy and a tentative mechanistic cycle has been proposed.

2020

An Efficient Approach to Fabricate Air-Stable Perovskite Solar Cells via Addition of a Self-Polymerizing Ionic Liquid

Nikita Drigo, Paul Joseph Dyson, Farzaneh Fadaei Tirani, Zhaofu Fei, Zhangjun Huang, Mohammad Khaja Nazeeruddin, Valentin Ianis Emmanuel Queloz, Cristina Roldán Carmona, Rosario Scopelliti, Rui Xia, Yi Zhang

Despite the excellent photovoltaic properties achieved by perovskite solar cells at the laboratory scale, hybrid perovskites decompose in the presence of air, especially at high temperatures and in humid environments. Consequently, high-efficiency perovskites are usually prepared in dry/inert environments, which are expensive and less convenient for scale-up purposes. Here, a new approach based on the inclusion of an in situ polymerizable ionic liquid, 1,3-bis(4-vinylbenzyl)imidazolium chloride ([bvbim]Cl), is presented, which allows perovskite films to be manufactured under humid environments, additionally leading to a material with improved quality and long-term stability. The approach, which is transferrable to several perovskite formulations, allows efficiencies as high as 17% for MAPbI(3)processed in air % relative humidity (RH) >= 30 (from an initial 15%), and 19.92% for FAMAPbI(3)fabricated in %RH >= 50 (from an initial 17%), providing one of the best performances to date under similar conditions.

2020

Nitrogen-Incorporated Cobalt Sulfide/Graphene Hybrid Catalysts for Overall Water Splitting

Lu Chen, Pengzuo Chen, Paul Joseph Dyson, Zhaofu Fei, Yun Tong

Water electrolysis is an advanced and sustainable energy conversion technology used to generate H-2. However, the low efficiency of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) hampers the overall water-splitting catalytic performance. Here, a hybrid catalyst was constructed from N-doped CoS(2)nanoparticles on N,S-co-doped graphene nanosheets (N-CoS2/G) using a facile method, and the catalyst exhibited excellent bifunctional activity. Introduction of N atoms not only promoted the adsorption of reaction intermediates, but also bridged the CoS(2)nanoparticles and graphene to improve electron transfer. Moreover, using thiourea as both N- and S-source ensured synthesis of much smaller-sized nanoparticles with more surface active sites. Surprisingly, the N-CoS2/G exhibited superior catalytic activity with a low overpotential of 260 mV for the OER and 109 mV for the HER at a current density of 10 mA cm(-2). The assembled N-CoS2/G : N-CoS2/G electrolyzer substantially expedited overall water splitting with a voltage requirement of 1.58 V to reach 10 mA cm(-2), which is superior to most reported Co-based bifunctional catalysts and other non-precious-metal catalysts. This work provides a new strategy towards advanced bifunctional catalysts for water electrolysis.

WILEY-V C H VERLAG GMBH2020

Selective Acceptorless Dehydrogenation of Primary Amines to Imines by Core-Shell Cobalt Nanoparticles

Matthias Beller, Xinjiang Cui, Paul Joseph Dyson, Zhaofu Fei

Core-shell nanocatalysts are attractive due to their versatility and stability. Here, we describe cobalt nanoparticles encapsulated within graphitic shells prepared via the pyrolysis of a cationic poly-ionic liquid (PIL) with a cobalt(II) chloride anion. The resulting material has a core-shell structure that displays excellent activity and selectivity in the self-dehydrogenation and hetero-dehydrogenation of primary amines to their corresponding imines. Furthermore, the catalyst exhibits excellent activity in the synthesis of secondary imines from substrates with various reducible functional groups (C=C, C equivalent to C and C equivalent to N) and amino acid derivatives.

2020

Transformation of Glucose to 5-Hydroxymethylfurfural Over Regenerated Cellulose Supported Nb2O5 center dot nH(2)O in Aqueous Solution

Lu Chen, Paul Joseph Dyson, Zhaofu Fei, Fangmin Huang

Niobic acid (Nb2O5 center dot nH(2)O) was immobilized on regenerated cellulose (Re-Cellulose) to afford a heterogeneous catalyst, termed Nb2O5 center dot nH(2)O@Re-Cellulose, that was characterized by powder X-ray diffraction, microscopy (SEM and TEM) and spectroscopic (Raman and FTIR) techniques. The surface acidity of the catalyst was determined using FTIR spectroscopy employing pyridine as a molecular probe. The Nb2O5 center dot nH(2)O@Re-Cellulose catalyst was investigated in the conversion of glucose into 5-hydroxymethylfurfural (HMF) in aqueous media. The catalyst can be reused several times without undergoing a significant loss in activity.

SPRINGER2020