TEM and EELS characterization of Ni–Fe layered double hydroxide decompositions caused by electron beam irradiation

Abstract

Electron irradiation of Ni–Fe layered double hydroxides (LDHs) was investigated in the transmission electron microscope (TEM). The initial structure possessed a flat hexagonal morphology made up of crystalline domains with a well-defined hexagonal crystal structure. The Ni–Fe LDHs were susceptible to significant structural decompositions during electron irradiation. The generation of pores and crystallographic breakdown of the LDH routinely occurred. In addition, a compositional change was established by electron energy loss spectroscopy (EELS). During 300 kV irradiation, a pre-peak evolution in the oxygen K edge highlighted a transition to metal oxide species. In parallel, nitrogen K edge attenuation demonstrated interlayer mass-losses. It was found that TEM conditions profoundly affected the decomposition behaviours. At lower acceleration voltages, an increased dehydration rate of the LDH cationic layers is observed during irradiaton. Moreover, in situ specimen cooling revealed the retention of interlayer nitrates. An emphasis on the dehydroxylation processes and anionic mass-loss facilitation is discussed.

IrOx@In2O3 Heterojunction from Individually Crystallized Oxides for Weak‐Light‐Promoted Electrocatalytic Water Oxidation

“…Peak i is reported to be attributable to the state core level excitations from O 1s to O 2p at the oxygen sites of metal, whereas peak ii emanates from the O 1s excitation to a hybridized state of the O 2p band with the 3d band of metals. This peak has been used to confirm the structural transformation from hydroxide to oxide [18] . Distinct signals of peak ii are observed at points 1 and 2; however, this peak disappears at points 3–5, suggesting that the surface of loaded IrO x particles is surrounded by ‐OH groups [18] .…”

“…This peak has been used to confirm the structural transformation from hydroxide to oxide [18] . Distinct signals of peak ii are observed at points 1 and 2; however, this peak disappears at points 3–5, suggesting that the surface of loaded IrO x particles is surrounded by ‐OH groups [18] . This means that loading an amount of IrO x can introduce a certain quantity of exposed surface ‐OH groups benefitting from the electrocatalytic water oxidation reaction.…”

Revealing nanoscale lithiation and dissolution pathways by in situ cryogenic electron microscopy

“…Simulated SAED (Fig. A.7.1) for the pristine ZnCo1.2Ni0.8O4 atomic structure in the[112] zone axis resembles the SAED pattern acquired from the core of the particle shown in Fig.7.7b. This observation indicates that the bulk structure of the particle is preserved after the OER cycling.…”

“…For example, biological molecules can be imaged only with doses below ~5 e − Å -2 (at liquid nitrogen temperature), organic crystals such as metal-organic frameworks (MOF) can be exposed to ~15-30 e − Å -2 , hybrid organicinorganic perovskites and zeolites are less sensitive and able to withstand doses of ~100-600 e − Å -2 [105][106][107][108][109][110]. Transition metal oxides can be imaged at doses in the range 10 5 -10 9 e − Å -2 [82,83,111,112]. An interested reader may refer to the following resources on electron beam damage in biological samples [79,[113][114][115][116], perovskites [117,118].…”

“…6.12e) shows mainly the diffusive halo ring, indicating that the crystal structure of the particles is amorphous (disordered), the spread of the distances is consistent with the La2LiIrO6 distances. In addition to the halo ring, a few reflections can be distinguished, which correspond to the 2.8 and 2.7 Å distances of (020), (112) planes in La2LiIrO6, respectively.…”