The environmentally friendly synthesis of highly active Fe‐N‐C electrocatalysts for proton‐exchange membrane fuel cells (PEMFCs) is desirable but remains challenging. A simple and scalable method is ...presented to fabricate FeII‐doped ZIF‐8, which can be further pyrolyzed into Fe‐N‐C with 3 wt % of Fe exclusively in Fe‐N4 active moieties. Significantly, this Fe‐N‐C derived acidic PEMFC exhibits an unprecedented current density of 1.65 A cm−2 at 0.6 V and the highest power density of 1.14 W cm−2 compared with previously reported NPMCs. The excellent PEMFC performance can be attributed to the densely and atomically dispersed Fe‐N4 active moieties on the small and uniform catalyst nanoparticles.
An environmentally friendly, facile, low‐cost, and scalable solid‐phase synthesis was developed for a highly active Fe‐N‐C electrocatalyst with iron exclusively in Fe‐N4 moieties. The as‐prepared Fe2‐Z8‐C delivered an unprecedented power density of 1.14 W cm−2 in acidic proton‐exchange membrane fuel cell, which was attributed to the densely and atomically dispersed Fe‐N4 active moieties and the small catalyst nanoparticles.
Abstract
Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report ...electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H
2
fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm
−2
). A nickel-modified cobalt phosphide (CoNi
0.25
P) electrocatalyst is developed to achieve a current density of 500 mA cm
−2
at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi
0.25
P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products.
Single atom catalyst, which contains isolated metal atoms singly dispersed on supports, has great potential for achieving high activity and selectivity in hetero-catalysis and electrocatalysis. ...However, the activity and stability of single atoms and their interaction with support still remains a mystery. Here we show a stable single atomic ruthenium catalyst anchoring on the surface of cobalt iron layered double hydroxides, which possesses a strong electronic coupling between ruthenium and layered double hydroxides. With 0.45 wt.% ruthenium loading, the catalyst exhibits outstanding activity with overpotential 198 mV at the current density of 10 mA cm
and a small Tafel slope of 39 mV dec
for oxygen evolution reaction. By using operando X-ray absorption spectroscopy, it is disclosed that the isolated single atom ruthenium was kept under the oxidation states of 4+ even at high overpotential due to synergetic electron coupling, which endow exceptional electrocatalytic activity and stability simultaneously.
Abstract
Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H
2
production. However, the corresponding current density is very low at ...moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H
2
production at high current density (540 mA cm
−2
at 1.5 V
vs
. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm
−2
) over 24 h with promoted productivity and decreased energy consumption.
Abstract
Atomic interface regulation is thought to be an efficient method to adjust the performance of single atom catalysts. Herein, a practical strategy was reported to rationally design single ...copper atoms coordinated with both sulfur and nitrogen atoms in metal-organic framework derived hierarchically porous carbon (S-Cu-ISA/SNC). The atomic interface configuration of the copper site in S-Cu-ISA/SNC is detected to be an unsymmetrically arranged Cu-S
1
N
3
moiety. The catalyst exhibits excellent oxygen reduction reaction activity with a half-wave potential of 0.918 V vs. RHE. Additionally, through in situ X-ray absorption fine structure tests, we discover that the low-valent Cuprous-S
1
N
3
moiety acts as an active center during the oxygen reduction process. Our discovery provides a universal scheme for the controllable synthesis and performance regulation of single metal atom catalysts toward energy applications.
The electrochemical reduction of CO2 could play an important role in addressing climate-change issues and global energy demands as part of a carbon-neutral energy cycle. Single-atom catalysts can ...display outstanding electrocatalytic performance; however, given their single-site nature they are usually only amenable to reactions that involve single molecules. For processes that involve multiple molecules, improved catalytic properties could be achieved through the development of atomically dispersed catalysts with higher complexities. Here we report a catalyst that features two adjacent copper atoms, which we call an ‘atom-pair catalyst’, that work together to carry out the critical bimolecular step in CO2 reduction. The atom-pair catalyst features stable Cu10–Cu1x+ pair structures, with Cu1x+ adsorbing H2O and the neighbouring Cu10 adsorbing CO2, which thereby promotes CO2 activation. This results in a Faradaic efficiency for CO generation above 92%, with the competing hydrogen evolution reaction almost completely suppressed. Experimental characterization and density functional theory revealed that the adsorption configuration reduces the activation energy, which generates high selectivity, activity and stability under relatively low potentials.Anchored single-atom catalysts have recently been shown to be very active for various processes, however, a catalyst that features two adjacent copper atoms—which we call an atom-pair catalyst—is now reported. The Cu10–Cu1x+ pair structures work together to carry out the critical bimolecular step in CO2 reduction.
Abstract
Developing effective catalysts based on earth abundant elements is critical for CO
2
electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current ...density of CO (
j
CO
) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N
3
site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a
j
CO
of 14.0 mA cm
−2
at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher
j
CO
of 29.7 mA cm
−2
is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N
3
site, which facilitates the formation of the key intermediate COOH
*
through a lowered free energy barrier.
Efficient, durable and inexpensive electrocatalysts that accelerate sluggish oxygen reduction reaction kinetics and achieve high-performance are highly desirable. Here we develop a strategy to ...fabricate a catalyst comprised of single iron atomic sites supported on a nitrogen, phosphorus and sulfur co-doped hollow carbon polyhedron from a metal-organic framework@polymer composite. The polymer-based coating facilitates the construction of a hollow structure via the Kirkendall effect and electronic modulation of an active metal center by long-range interaction with sulfur and phosphorus. Benefiting from structure functionalities and electronic control of a single-atom iron active center, the catalyst shows a remarkable performance with enhanced kinetics and activity for oxygen reduction in both alkaline and acid media. Moreover, the catalyst shows promise for substitution of expensive platinum to drive the cathodic oxygen reduction reaction in zinc-air batteries and hydrogen-air fuel cells.
Abstract
Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) ...electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N
4
structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H
2
O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A g
metal
−1
and a large turnover frequency of 5110 h
−1
at a low overpotential of 216 mV (10 mA cm
−2
), 480–510 times larger than those of the commercial IrO
2
. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.
Abstract
Benzene is a widely used commodity chemical, which is currently produced from fossil resources. Lignin, a waste from lignocellulosic biomass industry, is the most abundant renewable source ...of benzene ring in nature. Efficient production of benzene from lignin, which requires total transformation of C
sp2
-C
sp3
/C
sp2
-O into C-H bonds without side hydrogenation, is of great importance, but has not been realized. Here, we report that high-silica HY zeolite supported RuW alloy catalyst enables in situ refining of lignin, exclusively to benzene via coupling Bronsted acid catalyzed transformation of the C
sp2
-C
sp3
bonds on the local structure of lignin molecule and RuW catalyzed hydrogenolysis of the C
sp2
-O bonds using the locally abstracted hydrogen from lignin molecule, affording a benzene yield of 18.8% on lignin weight basis in water system. The reaction mechanism is elucidated in detail by combination of control experiments and density functional theory calculations. The high-performance protocol can be readily scaled up to produce 8.5 g of benzene product from 50.0 g lignin without any saturation byproducts. This work opens the way to produce benzene using lignin as the feedstock efficiently.
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