Figure 8.

(a) Effect of chemical doping leads to significant change in (003) peaks. Inset: close up of (003) peak, X‐ray data (SWAXS). Reproduced from Ref. [69] with permission from Elsevier, Copyright 2014. (b) HRXRD 2θ−ω scans of LSC films in their as‐prepared states and after vacuum annealing. The arrow showed the shift of the film peaks after vacuum annealing, indicating the chemical expansion introduced by oxygen vacancy formation. Reproduced from Ref. [73] with permission from WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim, Copyright 2019. (c) XPS spectra of O 1s of all as‐prepared Co₃O₄ catalysts. Reproduced from Ref. [74] with permission from The Royal Society of Chemistry, Copyright 2016. (d) Room‐temperature PL spectra of pristine and reduced NiCo₂O₄ (NCO) at 300 nm excitation wavelengths. Reproduced from Ref. [75] with permission from American Chemical Society, Copyright 2018.