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In this study, the influence of foreign and native point defects in magnesium oxide on the sintering process is examined. We have introduced dopants into magnesium oxide, with cations that share similar sizes but possess varying charges to minimize the direct impact of strain. The selected foreign cations were as follows: (1) Li1+, an acceptor that enhances the concentration of oxygen vacancies; (2) Sc3+, a donor that enhances the concentration of magnesium (metal) vacancies; and (3) Zn2+, an isovalent dopant. The results reveal that oxygen vacancies introduced by lithium doping greatly decrease the sintering temperature of magnesium oxide compared to the magnesium vacancies' effect (scandium doping). Zinc doping was found to increase the surface oxygen vacancies with only a minor effect on the sintering temperature. Enhancing the oxygen vacancy concentration by lithium doping creates an additional mechanism for sintering because the anion sublattice is the backbone of the material, and oxygen ion diffusion is the rate‐limiting step. Scandium doping also has a sintering–promoting effect, yet a minor one. The doping factor analysis is considered and implies that aliovalent dopants do not affect the concentration of the fast‐diffusing species, which are native vacancy associates. [ABSTRACT FROM AUTHOR]

We designed a heterostructure of Fe3S4@Ni3S2, as a potent oxygen evolution reaction (OER) electrocatalyst in an alkaline medium. Intriguingly, Fe3S4@Ni3S2 exhibits low onset potential of 290 mV and overpotential of 360 mV at a current density of 10 mA cm−2. We examined the OER kinetics of Fe3S4@Ni3S2 using distribution function of relaxation times (DFRT), which are attained with the help of impedance spectroscopy genetic programming (ISGP). ISGP reveals the occurrences of three events of OER, manifested as peaks in the DFRT, such as active material or pores (P2), charge transfer (P1'), and production rate of intermediates (P1) in case of Fe3S4@Ni3S2 at different faradic overpotentials. The effective resistance of each phenomenon can be easily calculated. It decreases with an increase in conductivity at high overpotentials for all the three, which suggests the high performance of the as‐synthesized composite due to faster kinetics. Further, structural investigation of the catalyst employing x‐ray photoelectron spectroscopy is elaborated and it is suggested that the catalyst activation takes place by the constant exchange of anions between electrode and electrolyte during electrochemical oxidation. [ABSTRACT FROM AUTHOR]