Photocatalytic reduction of CO2 to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO2 reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C3N4/FeWO4 composites are prepared for higher performance and selective CO2 reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO4 nanoparticles with C3N4 nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 μmol/g/h at an ambient temperature, almost 6 times higher compared to pristine C3N4 and 15 times higher than pristine FeWO4. More importantly, selectivity for CO is 100% over other carbon products from CO2 reduction and more than 90% over H2 products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO4 and C3N4 reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron–hole pair in g-C3N4/FeWO4 but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO2 reduction into solar fuels under solar light.

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We report the sensing properties of an interesting ternary oxide CuCo 2 O 4 (CCO) which comprises two earth-abundant transition elements, both capable of supporting multiple valence states. We have used a synthesis protocol, which renders unique nanoplatelet-type morphology but with a degree of biphasic character (CuO as a secondary phase in addition to the defect-spinel Cu 1– x Co 2 O 4 ). This sample constitution can be controlled through the use of cation off-stoichiometry, and the same also influence the sensing response significantly. In particular, a Co 10 at. % excess CCO (CCO–Co(10)) case exhibits a good response (∼7.9% at 400 ppm) for NH 3 gas with a complete recovery at room temperature (23 °C, ±1 °C) in 57% RH. The material performance was investigated for other gases such as H 2 S, NO 2 , and CO. A good response is observed for H 2 S and NO 2 gases but without a recovery; however, for CO, a poor response is noted. Herein, we discuss the specific results for ammonia sensing for the CCO–Co(10) case in detail via the use of different characterizations and outline the difference between the cases of the single-phase defect-stabilized material versus nonpercolating biphasic material.

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An ab initio calculations have been carried out for examining the curvature effect of small diameter hexagonal boron nanotubes. The considered conformations of boron nanotubes are namely armchair (3,3), zigzag (5,0) and chiral (4,2), and consist of 12, 20, and 56 atoms, respectively. The strain energy is evaluated in order to examine the curvature effect. It is found that the strain energy of hexagonal BNT strongly depends upon the radius, whereas the strain energy of triangular BNTs depends on both radius and chirality.