Synthesis and hierarchical pore structure of biomorphic manganese oxide derived from woods

Biomorphic manganese oxides on two different wood templates (fir and paulownia) were fabricated by infiltration with nitrate and subsequently calcination. X-ray diffraction (XRD) test and microscopy observation (FESEM and TEM) were employed to characterize the phase and structure of biomorphic manganese oxides. The pore structure of the resulting products was studied through mercury intrusion and nitrogen adsorption measurement. Infrared (IR) adsorption properties were investigated by Fourier Transmission Infrared (FTIR). The final oxide products contain hierarchical pore structure from μm to nm scale, and also show unique pore size and distribution with hierarchy on nanoscale derived from the specific wood template, the changeable connectivity of nanoscale pore channel controlled by calcinations temperature. The rise of temperature leads to diminishing of average pore diameter and volume but more uniform pore size distribution and higher degree of pore connectivity. The overall collapse in IR adsorption spectra of biomorphic manganese oxides with the rise of calcination temperature is related to the effect of nanoscale pore structure especially the increasing of pore connectivity.