Gd and Co-substituted LaNiO3 and their nanocomposites with r-GO for photocatalytic applications

From the past few decades, rapid industrializations of the world communities have seriously influenced our natural ecosystem. The efforts to develop/invent a novel material as a photocatalyst for non-degradable organic contaminants are keen need for recent ages. We report Gd and Co-doped LaNiO3 (La1-yGdyNi1-xCoxO3) synthesized via co-precipitation method and nanocomposites was prepared with 10% reduced graphene oxide (r GO) via ultra-sonication method. The synthesized materials were characterized by XRD, FTIR and Raman spectroscopy to investigate their structure and allowed Raman vibrations. The particle size, shape, and elemental compositions were examined by SEM and EDX analysis. The La1-yGdyNi1-xCoxO3/rGO nanocomposites possessed extensive BET surface area (134 m(2)/g) compared to pristine LaNiO3 (77 m(2)/g) and La1-yGdyNi1-xCoxO3 (89 m(2)/g). The photocatalytic properties of as-prepared materials were enhanced by extensive BET surface area. The effect of doping and the addition of r-GO on the electrical conductivity of the fabricated materials were investigated via two probe current-voltage (I-V) tests. Energy band gap (Eg) were calculated from UV-visible absorbance spectra using Tauc plots., band gap values shows a decreasing trend by increasing dopant Gd and Co content i.e. 2.80 (eV) to 2.07 (eV) for doped samples, and subsequently decrease on composites formation 1.90 (eV). Narrowing in the band gap value is considered very important for many optical and catalytic applications. For application studies, the photocatalytic activities of the fabricated photocatalyst were tested under natural sunlight by using methylene blue (MB) as a typical contaminant. After 90 min of irradiation, the pristine LaNiO3 photocatalyst degraded 26.3% of MB dye, while Gd and Co-doped LaNiO3 degraded 47.1% of MB dye. Surprisingly, the La1-yGdyNi1-xCoxO3/r-GO nanocomposites photocatalyst degraded 81.4% of MB, which is faster than the pristine LaNiO3 photocatalyst. The enhancement in the degradation efficiency and degradation rate of La1-yGdyNi1-xCoxO3/r-GO nanocomposites is accredited to its novel structures and r-GO supplement. The material with narrow band gap and high electrical conductivity are good choice as catalyst and other optical applications.