Visible-light-driven hydrogen evolution with high efficiency is important in the current photocatalysis research. Here we report for the first time the design and synthesis of a new graphene–semiconductor nanocomposite consisting of YInO3 nanoparticles and two-dimensional graphene sheets as efficient photocatalysts for hydrogen evolution under visible light irradiation. The graphene/YInO3 nanocomposites were synthesized using a facile solvothermal method in which the formation of graphene and the deposition of YInO3 nanoparticles on the graphene sheets can be achieved simultaneously. The addition of graphene as a cocatalyst can narrow the band gap of YInO3 to visible photon energy and prolong the separation and lifetime of electron–hole pairs by the chemical bonding between YInO3 and graphene. The photocatalytic reaction with this nanocomposite reaches a high H2 evolution rate of 400.4 μmol h−1 g−1 when the content of graphene is 0.5 wt%, over 127 and 3.7 times higher than that of pure YInO3 and Pt/YInO3, respectively. This work can provide an effective approach to the fabrication of graphene-based photocatalysts with high performance in the field of energy conversion.
Near infrared reflective inorganic pigment YIn 1-x-y Mn y Fe x O 3 (x/y = 0.1–0.5) was prepared by solid state reaction. The X-ray diffraction analysis and CIE1976 L*a*b* colorimetric analysis reveal that the main phase of the sample is changed from YInO 3 phase to YFeO 3 phase and the color of the sample is changed from blue to black (x ≥ 0.4) with the increase of iron content. The brightness value of black pigment ranges from 23.27 to 32.12. When In 3+ is replaced by Fe 3+ and Mn 3+ , the band gap of the black sample is decreased from 1.73eV to 1.39eV. The near-infrared reflectance (R) and near-infrared solar reflectance (R*) of the sample reach the maximum when x = 0.4 and y = 0.1, which are 77.82% and 53.44%, respectively. YIn 1-x-y Mn y Fe x O 3 (x = 0.4–0.5, y = 0.1–0.5) black samples have higher near infrared reflectivity than common commercial black pigments. In the thermal insulation study, under the condition of infrared irradiation for 90 min, the internal air temperature difference between the iron car model coated with YIn 0.5 Mn 0.1 Fe 0.4 O 3 pigment and the iron car model coated with commercial iron black pigment can reach 7 °C. YIn 0.5 Mn 0.1 Fe 0.4 O 3 black pigment was soaked in 5% acid-alkali solution for 24 h, the chromaticity was almost unchanged before and after immersion, indicating that the sample has good chemical stability. The above properties show the potential of synthetic black pigments in the field of energy conservation.
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