近日，中国科学技术大学周仕明教授、曾杰等人在JACS上发表重要文章，论文题为“TuningtheElectronicandStericInteractionattheAtomicInterfaceforEnhancedOxygenEvolution”。非均相催化剂的二维表面或一维界面对于确定所需活性的反应中间体的吸附强度和构型至关重要。最近，单原子催化剂的发展使人们能够在原子水平上理解催化过程。然而，一维界面的传统概念和机制是否适用于零维单原子仍然不清楚。在这项工作中，作者安排了单个原子的位置，来探索它们的界面相互作用以改善氧气的释放。当铱单原子被限制在CoOOH的晶格中时，Ir和Co之间的有效电子转移调节了氧化中间体的吸附强度。相比之下，锚定在CoOOH表面上的原子铱物种会导致电子结构发生不可察觉的改变，而在其Ir-OH-Co界面与关键中间体的空间相互作用在降低其析氧能垒方面发挥了主要作用。
第一作者：ChenFeng通讯作者：ShimingZhou,JieZeng通讯单位：中国科学技术大学论文DOI：10./jacs.2cFigure1.Mechanisticstudiesoflattice-dopedandsurface-adsorbedIrsingleatomsonCoOOH.SchematicstructuremodelofIr1/CoOOHlatfrom(a)sideand(b)topviews.SchematicstructuremodelofIr1/CoOOHsurfrom(c)sideand(d)topviews.(e)PDOSofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.Thered,blue,andyellowlinesrepresentthePDOSofO,Co,andIr,respectively.(f)Cod-bandcenterofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.(g)Free-energydiagramsofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsurtowardOER.TheinsetsdisplaytheadsorptionofintermediatesateachsteponIr1/CoOOHsur.Thegraydashedlinesindicatehydrogenbonding.Theblackdashedlinehighlightsthehydrogenbondingbetweensurface-adsorbedIr(OH)6andthe*OOHintermediate,thebondlengthofwhichis2.1?.Thewhite,red,purple,andyellowspheresrepresentH,O,Co,andIratoms,respectively.
Figure2.StructuralcharacterizationsofIr1/CoOOHlatandIr1/CoOOHsur.HAADF-STEMimagesof(a)Ir1/CoOOHlatand(b)Ir1/CoOOHsur.Singly-dispersedIratomsareindicatedbyyellowcircles.EDXelementalmappingof(c)Ir1/CoOOHlatand(d)Ir1/CoOOHsur.Normalized(e)XANESand(f)EXAFSspectraattheIrL3-edgeforIr1/CoOOHlatandIr1/CoOOHsur.IrO2andIrfoilwereusedasreferences.(g)ExperimentalandfittingEAXFSspectraattheIrL3-edgeofIr1/CoOOHlatandIr1/CoOOHsur.Theexperimentalandfittingresultsareshownassolidlinesandcircles,respectively.Theinsetsdemonstratethefirst-shellcoordinationtoIrcentersofIr1/CoOOHlatandIr1/CoOOHsuraccordingtothefittingresults.TheredandyellowspheresrepresentOandIratoms,respectively.Normalized(h)XANESand(i)EXAFSspectraattheCoK-edgeforCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.CoOandCofoilwereusedasreferences.
Figure3.ElectrocatalyticperformancestowardOER.(a)PolarizationcurvesofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.IrO2wasusedasreference.Themeasurementswereconductedin1.0MKOH.(b)Overpotentialsat10mAcm–2forCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.SpecificactivitiesofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsurnormalizedagainst(c)ECSAand(d)theirspecificactivitiesatanoverpotentialofmV.(e)TafelslopesofCoOOH,Ir1/CoOOHlat,andIr1/CoOOHsur.(f)ChronopotentiometriccurvesofIr1/CoOOHsurtowardOERat10mAcm–2for24h.
Figure4.Insituspectroscopiccharacterizations.(a)InsituRamanspectraofIr1/CoOOHsuratdifferentappliedpotentials.InsituATR–FTIRspectraof(b)CoOOH,(c)Ir1/CoOOHlat,and(d)Ir1/CoOOHsurunderdifferentappliedpotentials.AllpotentialswerenormalizedagainstRHE.作者通过将单个原子锚定在CoOOH的不同位置构建了两个不同的界面，这通过两种机制控制了析氧中间体的吸附。将铱单原子掺杂到CoOOH(Ir1/CoOOHlat)的晶格中会产生电子重新分布以加强所有中间体的吸附。尽管将原子铱物种锚定到CoOOH的表面（Ir1/CoOOHsur）引起了微不足道的电子变化，但其Ir-OH-Co界面处的空间相互作用设计了关键中间体*OOH的吸附，这一点通过原位ATR-FTIR中减弱的O-O振动得到证实。因此，这种相互作用稳定了*OOH，并将Ir1/CoOOHsur的RDS能垒降低到1.65eV，优于Ir1/CoOOHlat的(1.85eV)。电化学测试证实，Ir1/CoOOHsur的OER仅需mV的过电位即可达到10mAcm-2，比Ir1/CoOOHlat低mV。这项工作不仅区分了电子和空间效应在调节反应中间体吸附中的作用，而且还提供了对促进催化过程的有效原子界面的见解。文献获取方式：添加小编
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