Abstract
This research highlights the pressure effects with the particle size dependency incorporated in two-dimensional graphene oxide (GO)/reduced graphene oxide (rGO). GO and rGO composites employing nanorods (NRs) of type [Fe(Htrz)2(trz)](BF4) have been prepared, and their pressure effects in the interlayer spaces through observing the changes of the spin crossover (SCO) temperature (T1/2) have been discussed. The composites show the decrease of interlayer spaces from 8.7 Å to 3.5 Å that is associated with GO to rGO transformation. The shorter interlayer spaces were induced by pressure effects, resulting in the increment of T1/2 from 357 K to 364 K. The pressure effects in the interlayers spaces estimated from the T1/2 value correspond to 24 MPa in pristine [Fe(Htrz)2(trz)](BF4) NRs under hydrostatic pressure. The pressure observed in the composites incorporating NRs (30 × 200 nm) is smaller than that observed in the composite incorporating nanoparticles (NPs) (30 nm). These results clearly demonstrated that the incorporated particle size and shape influenced the pressure effects between the GO/rGO layer.
Highlights
Van der Waals interactions in the pores of micro-porous materials are known to generate a pseudo-pressure effect, leading to the expression of characteristic phases and unique properties in the pores under mild conditions. [1,2,3,4,5,6]
Pressure corresponding to 1.2 ± 0.3 GPa was observed by trapping pressure-sensitive molecules of triphenyl amine (TPA) and boric acid (BA) into an interlayer of graphene [9]
The scanning electron microscopy (SEM) images and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) data were collected on a JEOL, JSM-7600 F instrument (Akishima-shi, Tokyo, Japan)
Summary
Van der Waals interactions in the pores of micro-porous materials are known to generate a pseudo-pressure effect, leading to the expression of characteristic phases and unique properties in the pores under mild conditions. [1,2,3,4,5,6]. In typical 2D layered materials, the correlations between pressure (P) and the interlayer distance (d) were estimated using the equation of P ≈ Ew/d, where Ew is the adhesion energy [11,12]. 2D materials that possess a tunable interlayer have the possibility of tuning pressure effects, leading to the generation of unique phases and physical properties. Magnetochemistry 2019, 5, x FOR PEER REVIEW of [Fe(Htrz)2(trz)](BF4) was clearly confirmed by the energy dispersive X-ray (EDX) spectroscopy ((FFiigguurrees2c2,cda).ndThde).FTohuerFieorutrriaenrstfroarnmsfoinrmfrairnefdrasrpedecstpraec(tFrTa-(IFRT)-rIeRs)urletssualltssoaslsuopspuoprpteodrttehdetphreepserensceenocfe [oFfe[(FHet(rHz)t2r(zt)r2z(t)r](zB)]F(4B)FN4)RNsRcsomcopmopsiotesidtewdiwthiitnhitnhethGeOG/rOG/rOGiOntienrtlearylearyse(rFsi(gFuirgeuSre3)S. AAss ffoorr ccoommppoossiittee11,,tthheeGGOOppeeaakkwwaassoobbsseerrvveeddaatt22θθ== 100..1177◦ ̊ and an interlayer distance of 8.68 Å, whheerree tthhee rreemmaaiinniinnggppeeaakkssaarreeaassccrriibbeeddttootthheepprreesseenncceeooff[F[Fee(H(Htrtrzz)2)2((ttrrzz))]]((BBFF44)) NNRRss. In the case ooff ccoommppoossiittee 22 ((wwhhiicchhwwaasstrtreeaateteddaat t447733KKfofror1212h)h, )t,htehienitnertelarylaeyredrisdtiasntacnecdeedcreecarseeadsetdo 3to.53Å.5(Å2θ(2=θ2=5◦2)5as) asreasruelstuolft tohfetrheemroevmaloovfatlhoefoxthyegeonxfyugnecntiofunnalctgiroonuapl sgornouthpes GoOn ltahyeerGs.OFrloamyerths.esFeroremsutlhtse,siet craensubletsa,nitticcipanatebde tahnatticpirpeastseudretheafftepcrtsesoscucruerereffdecbtestowceceunrrtehde binetewrleaeynerths.e interlayers. Summary of spin crossover (SCO) temperatures (T1/2) and pseudo-pressure
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