Novel P-doping-tuned Pd nanoflowers/S,N-GQDs photo-electrocatalyst for high-efficient ethylene glycol oxidation

Traditional photo-electcatalyst structures of small noble metal nanoparticles assembling into large-scale photoactive semiconductors still suffer from agglomeration of noble metal nanoparticles,insufficient charge transfer,undesirable photoresponse ability that restricted the photo-electrocatalytic performance.To this end,a novel design strategy is proposed in this work,namely integrating small-scale photoactive materials(doped graphene quantum dots,S,N-GQDs)with large-sized noble metal(Pd P)nanoflowers to form novel photo-electrocatalysts for high-efficient alcohol oxidation reaction.As expected,superior electrocatalytic performance of Pd P/S,N-GQDs for ethylene glycol oxidation is acquired,thanks to the nanoflower structure with larger specific surface area and abundant active sites.Furthermore,nonmetal P are demonstrated,especially optimizing the adsorption strength,enhancing the interfacial contact,reducing metal agglomeration,ensuring uniform and efficient doping of S,N-GQDs,and ultimately significantly boost the catalytic activity of photo-electrocatalysts.

Nanostructure and Formation Mechanism of Pt-WO_3/C Nanocatalyst by Ethylene Glycol Method

Pt-WO3 nanoparticles uniformly dispersed on Vulcan XC-72R carbon black were prepared by an ethylene glycol method.The morphology,composition,nanostructure,electrochemical characteristics and electrocatalytic activity were characterized,and the formation mechanism was investigated.The average particle size was 2.3 nm,the same as that of Pt/C catalyst.The W/Pt atomic ratio was 1/20,much lower than the design of 1/3.The deposition of WO3·xH2O nanoparticles on Vulcan XC-72R carbon black was found to be very difficult by TEM.From XPS and XRD,the Pt nanoparticles were formed in the colloidal solution of Na2WO4,the EG insoluble Na2WO4 resulted in the decreased relative crystallinity and increased crystalline lattice constant compared with those of Pt/C catalyst and,subsequently,the higher specific electrocatalytic activity as determined by CV.The Pt-mass and Pt-electrochemically-active-specific-surface-area based anodic peak current densities for ethanol oxidation were 422.2 mA·mg-1Pt and 0.43 mA·cm-2Pt,1.2 and 1.1 times higher than those of Pt/C catalyst,respectively.

Co-electrolysis of ethylene glycol and carbon dioxide for formate synthesis

Co-electrolysis of waste plastics and carbon dioxide(CO_(2)) into value-added chemicals or fuels is a promising pathway for a sustainable society, but efficient and selective conversion remains a challenge. Herein, a gold-mediated nickel hydroxide(Au/Ni(OH)_(2)) is developed to oxidize waste plastic-derived ethylene glycol(EG) into formate. In-situ electrochemical experiments and theoretical results reveal that the introduction of Au favors the redox properties and EG adsorption behavior of Ni(OH)_(2). The Au/Ni(OH)_(2) catalyst shows an excellent formate selectivity of >90% at high current densities of above 100 m A cm^(-2). When coupled with sputtered bismuth(Bi) cathode for CO_(2) reduction, a high formate Faradic efficiency(FE) of 188.2% at 200 m A cm^(-2)and a good formate productivity of 7.33 mmol m^(-2)s^(-1)at 10 A are obtained in a flow cell and a zero-gap membrane electrode assembly(MEA) cell, respectively. This work demonstrates a promising strategy to convert waste plastics and CO_(2) into valuable products.

Fabrication of 3D hollow acorn-shell-like PtBi intermetallics via a surfactant-free pathway for efficient ethylene glycol electrooxidation

The synthesis of atomically ordered Pt-based intermetallic electrocatalysts for the direct alcohol fuel cells generally requires the addition of surfactants or the high-temperature annealing.However,some residual surfactants on the surface of the assynthesized catalysts would prevent the exposure of catalytic active sites,the high-temperature annealing process is easy to accelerate the sintering of the metal,which both lead to the decline of electrocatalytic performance.Herein,we construct the atomically ordered bimetallic PtBi intermetallics with clean surfaces and unique three-dimensional hollow acorn-shell-like structure(3D PtBi HASL)by a simple,low-temperature,surfactant-free one-pot synthetic approach.Benefiting from the special hollow structures,the obtained 3D PtBi HASL intermetallics expose abundant accessible active sites.Moreover,the introduction of oxophilic metal Bi can enhance adsorption of OHads,thereby significantly facilitating removal of poisoned intermediates.Density functional theory(DFT)simulations further indicate that formation of the PtBi intermetallic phase with the downshift of the Pt d-band center endows 3D Pt49.4Bi50.6 HASL intermetallics with significantly attenuated COads and enhanced OHads adsorption,bringing about the boosting electrocatalytic property.The mass activity of the 3D Pt49.4Bi50.6 HASL intermetallics for ethylene glycol oxidation reaction is as high as 24.67 A·mgPt^(−1),which is 12.98 times higher than that of commercial Pt/C(1.90 A·mgPt^(−1)).This work may inspire the design of Pt-based intermetallics as high-efficiency anode electrocatalysts for fuel cell applications.

Controlled synthesis of MOF-derived hollow and yolk–shell nanocages for improved water oxidation and selective ethylene glycol reformation

Delicately designed metal–organic framework(MOF)-derived nanostructured electrocatalysts are essential for improving the reaction kinetics of the oxygen evolution reaction and tuning the selectivity of small organic molecule oxidation reactions.Herein,novel oxalate-modified hollow CoFe-based layered double hydroxide nanocages(h-CoFe-LDH NCs)and yolk–shell ZIF@CoFe-LDH nanocages(ys-ZIF@CoFe-LDH NCs)are developed through an etching–doping reconstruction strategy from a Co-based MOF precursor(ZIF-67).The distinctive nanostructures,along with the incorporation of the secondary metal element and intercalated oxalate groups,enable h-CoFe-LDH NCs and ys-ZIF@CoFe-LDH NCs to expose more active sites with high intrinsic activity.The resultant h-CoFe-LDH NCs exhibit outstanding OER activity with an overpotential of only 278 mV to deliver a current density of 50 mA cm^(-2).Additionally,controlling the reconstruction degree enables the formation of ys-ZIF@CoFe-LDH NCs with a yolk–shell nanocage nanostructure,which show outstanding electrocatalytic performance for the selective ethylene glycol oxidation reaction(EGOR)toward formate,with a Faradaic efficiency of up to 91%.Consequently,a hybrid water electrolysis system integrating the EGOR and the hydrogen evolution reaction using Pt/C||ys-ZIF@CoFe-LDH NCs is explored for energy-saving hydrogen production,requiring a cell voltage 127 mV lower than water electrolysis to achieve a current density of 50 mA cm^(-2).This work demonstrates a feasible way to design advanced MOF-derived electrocatalysts toward enhanced electrocatalytic reactions.

PdPbBi nanoalloys anchored reduced graphene-wrapped metal-organic framework-derived catalyst for enhancing ethylene glycol electrooxidation

For future clean energy demand,it is essential to develop highly efficient and durable materials for use in renewable energy conversion devices.Herein,we report an electrocatalyst loaded with Pd-Pb-Bi nanoalloys on reduced graphene(rGO)-wrapped In_(2)O_(3)(PdPbBi@rGO/In_(2)O_(3))prepared by a hydrothermal method.PdPbBi@rGO/In_(2)O_(3)exhibits higher forward current density(229.12 mA·cm^(-2)),larger electrochemical active surface area(ECSA)(85.87 m^(2)·g^(-1)Pd),smaller impedance(12.68Ω)and lower E_(onset)(-0.56 V)than commercial Pd/C.Specifically,the current density and ECS A are 8.46 and3.38 times higher than those of commercial Pd/C(27.07 mA·cm^(-2),25.41 m^(2)·g^(-1)Pd),respectively.Furthermore,the oxidation mechanism of ethylene glycol and the removal of carbon monoxide[CO]_(ads)from the surface of Pd are also discussed in detail.The columnar support structure wrapped by rGO provides a huge active surface area for catalysis.Moreover,the electronic effect of Pd-PbBi nanoalloys can accelerate the removal of CO intermediate species,obtain more Pd active sites and improve the electrocatalytic performance.Our first synthesis of this highly electrocatalyst offers promising value for commercial application in direct fuel cells.

Paired formate and H_(2) productions via efficient bifunctional Ni-Mo nitride nanowire electrocatalysts

Electrocatalytic water splitting provides a potentially sustainable approach for hydrogen production,but is typically restrained by kinetically slow anodic oxygen evolution reaction(OER)which is of lesser value.Here,free-standing,hetero-structured Ni_(3)N-Ni_(0.2)Mo_(0.8)N nanowire arrays are prepared on carbon cloth(CC)electrodes for hydrogen evolution reaction(HER)and glycerol oxidation reaction(GOR)to formate with a remarkably high Faradaic efficiency of 96%.A two-electrode electrolyzer for GOR-assisted hydrogen production operates with a current density of 10 mA cm^(-2)at an applied cell voltage of 1.40 V,220 mV lower than for alkaline water splitting.In-situ Raman measurements identify Ni(Ⅲ)as the active form of the catalyst for GOR rather than Ni(IV)and in-situ Fourier transform infrared(FTIR)spectroscopy measurements reveal pathways for GOR to formate.From density functional theory(DFT)calculations,the Ni_(3)N-Ni_(0.2)Mo_(0.8)N heterostructure is beneficial for optimizing adsorption energies of reagents and intermediates and for promoting HER and GOR activities by charge redistribution across the heterointerface.The same electrode also catalyzes conversion of ethylene glycol from polyethylene terephthalate(PET)plastic hydrolysate into formate.The combined results show that electrolytic H_(2) and formate production from alkaline glycerol and ethylene glycol solutions provide a promising strategy as a cost-effective energy supply.

Upcycling PET in parallel with energy-saving H_(2)production via bifunctional nickel-cobalt nitride nanosheets

We describe here an electro-reforming strategy to upcycle polyethylene terephthalate(PET)waste with simultaneous hydrogen production by a bifunctional nickel-cobalt nitride nanosheets electrocatalyst.PET plastics are digested in alkaline solution giving an electrochemically active monomer ethylene glycol(EG).The introduction of Co in Co-Ni3N/carbon cloth(CC)promotes the redox behavior of Ni2+/Ni3+,which is beneficial for EG oxidation at an ultra-low potential(1.15 V vs.reversible hydrogen electrode(RHE))and breaks through the limitation of high catalytic potentials of simple Ni-based electrocatalysts(1.30 V).In PET hydrolysate with Co-Ni3N/CC couples,an integrated EG oxidation-hydrogen production system achieves a current density of 50 mA·cm^(−2)at a cell voltage of 1.46 V,which is 370 mV lower than the conventional water splitting.The in-situ Raman and Fourier transform infrared(FTIR)spectroscopies and density functional theory(DFT)calculations identify the catalytic mechanism and point to advantages of heterostructure engineering in optimizing adsorption energies and promoting catalytic activities for EG oxidation.