Tuneable pressure effects in graphene oxide layers

Tuneable pressure effects associated with changing interlayer distances in two-dimensional graphene oxide (GO)/reduced GO (rGO) layers are demonstrated through monitoring the changes in the spin-crossover (SCO) temperature (T1/2) of [Fe(Htrz)2(trz)](BF4) nanoparticles (NPs) incorporated in the interlayer spaces of the GO/rGO layers. The interlayer separation along the GO to GO/rGO-NP composites to rGO series decreases smoothly from 9.00 Å (for GO) to 3.50 Å (for rGO) as the temperature employed for the thermal reduction treatments of the GO-NP composites is increased. At the same time, T1/2 increases from 351 K to 362 K along the series. This T1/2 increment of 11 K corresponds to that observed for pristine [Fe(Htrz)2(trz)](BF4) NPs under a hydrostatic pressure of 38 MPa. The influence of the stacked layer structures on the pseudo-pressure effects has been further probed by investigating the differences in T1/2 for [Fe(Htrz)2(trz)](BF4) that is present in the composite as larger bulk particles rather than as NPs.