Preparation of molybdenum carbides with multiple morphologies using surfactants as carbon sources

Influence of Electrostatic Interactions During the Resorcinol-Formaldehyde Polymerization on the Characteristics of Mo-Doped Carbon Gels

“…The region Mo3d was also fitted using two components. The Mo 6+ in MoO 3 presents a characteristic d 5/2 and d 3/2 doublet at ≈232.9 and ≈236.0 eV, respectively, with a separation between peaks of 3.2 eV [35], in good agreement with the results obtained for MoA-SC-pH7 (Figure 1g), where the Mo3d 5/2 and Mo3d 3/2 components are centered at ≈233.3 and ≈236.4 eV, respectively. When cationic Mo 5+ was used as precursor, the analysis indicates that Mo 5+ was oxidized during the sol-gel synthesis, being as Mo 6+ in both MoC-SC-pH7 and MoC-SA-pH7 samples (Figure 1e,f, respectively).…”

“…Nevertheless, in our previous studies, the formation of highly crystalline β-Mo 2 C in Mo-doped carbon xerogels was detected using MoA-SC combinations in acidic conditions, however, a higher TMB/t-BuOH concentration was used [16]. When cationic CTAB and Mo 5+ were used (MoC-SC-pH7 sample), intense diffraction peaks at ≈34.4, ≈37.9, ≈39.5, ≈52.2, ≈61.7 and ≈69.6 • corresponding to the (100), (002), (101), (110) and (103) planes of hexagonal β-Mo 2 C (JCPDS 35-0787) were observed, denoting the high crystallinity of this phase [35]. Nevertheless, none of the possible intermediate molybdenum oxides (MoO x ) were detected, pointing out that these phases are mainly amorphous.…”

“…Figure 6 depicted the Mo3d region for carbon samples obtained with different combinations of anionic and cationic surfactants and metal precursors, the different chemical state of Mo in each sample being obvious at a glance. The Mo3d spectra of the MoA-SA-pH7 sample (both anionic surfactant and metal precursor, Figure 6a) was fitted using only a doublet, the peaks at ≈232.9 and ≈236.0 eV corresponding to the d 5/2 and d 3/2 components of Mo 6+ in MoO 3 [35], as previously described. The oxide should be mainly amorphous, taking into account the previous XRD ( Figure 5).…”

High-Temperature Corrosion of UNS N10003 in Molten Li2BeF4(FLiBe) Salt

“…The characteristic peaks of the matrix FCC austenite phase are clearly identifiable on the three types of samples. [34][35][36][37][38][39] This analysis is consistent with the EDS analysis of post-corrosion alloy surface shown in Figure 3(b). Mo is known to be relatively inert in molten fluoride salt environment.…”