Simple route deposition and some physical investigations on nanoflower NiMoO4 sprayed thin films

Recent developments and future perspectives on energy storage and conversion applications of nickel molybdates

“…Gassoumi et al recently termed NiMoO 4 thin film to be semitransparent in visible and infrared range (T\60%), and reflectance ranges amid 12% and 20% by transmittance and reflectance measurement, respectively (Figure 12B). As per their findings, the optical band gap for β‐NiMoO 4 is a little bit higher than the α‐counterpart 89 . The extinction coefficient reduces and forms a minimum at 400 to 600 nm range.…”

“…Alternatively, the optical band gap can also be obtained from direct reflectance measurement spectra (DRS) using Kubelka‐Munk equation 81 . Table 2 summarizes a few critical estimations of the optical bandgap for NiMoO 4 done by several researchers 52,57,59,82‐92 . It is clear that an average optical band gap of NiMoO 4 lies in the range ~1.5 to 3 eV, designating it as a semiconductor at ambiance and in principle a good candidate for utilization as a photocatalyst 93 .…”

“…B, Transmission and reflectance spectra of NiMoO 4 nanoflower. C, Variation of extinction coefficient as a function of wavelength 89 . D, The UV‐DRS absorbance spectra and, the density of states 57 .…”

“…The energy parting between the maxima of these bands is close to 3 eV, giving them a confined character. In Gassoumi et al's work, a PL emission study was done with NiMoO 4 containing high dislocation density with 270 nm excitation wavelength 89 . Interestingly, while deconvoluted, the large, non‐symmetric broad‐band resultant spectrum results in adjustment with seven different emission peaks or contribution of seven energy stages or light release centers able to embed electrons inside the bandgap.…”

“…The numbers in digressions specify the degeneracy of the [MoO 4 2− ] complex, with the “*” demonstrating anti‐bonding (unoccupied) statuses 98 . C, PL spectrum with Gaussian deconvolution and, D, schematic illustration of the photoluminescence mechanism for NiMoO 4 nanoflower‐sprayed thin film 89 . Reproduced with permission…”