Abstract
Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C3N4/melamine sponge (g-C3N4/MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C3N4 on MS skeleton. The monolithic g-C3N4/MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C3N4/MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal and CO2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C3N4, and yield rate of CO and CH4 attains 7.48 and 3.93 μmol g−1 h−1. Importantly, the features of low-density, high porosity, good elasticity, and firmness, not only endow g-C3N4/MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.
Highlights
Semiconductor photocatalysis is one of the promising strategies for pollutants abatement (Maggos et al, 2007; Huang et al, 2013, 2016; Zhao et al, 2015) and has attracted intense investigation in the past decades
To obtain the best photocatalytic activity of monolithic g-C3N4/melamine sponge (MS), we finely investigated the effect of gC3N4 suspension concentration (3 mg mL−1-40 mg mL−1) and MS thickness (0.5–2.5 cm)
The pretreated MS was immersed into this suspension through dipping and squeezing procedures until MS was fully covered by g-C3N4 particles
Summary
Semiconductor photocatalysis is one of the promising strategies for pollutants abatement (Maggos et al, 2007; Huang et al, 2013, 2016; Zhao et al, 2015) and has attracted intense investigation in the past decades. The intrinsic brittleness and weak firmness of aerogels make it easy to break into pieces during mechanical deformation, which seriously restrict its potential in practical application Other firm supports, such as carbon foam and Al2O3 ceramic foam with hard 3D framework, are selected to fabricate monolithic photocatalyst (Dong et al, 2014b; Lin et al, 2016). The as-prepared monolithic photocatalyst exhibits low-density, high porosity, high elasticity and good firmness, which make it flexible in various environmental applications including NO removal, and CO2 photoreduction, and make it easy to recycle and suitable for practical application. Where NA represents Avogadro’s constant (6.02×1023 mol−1), AMB represents the covered area of per MB molecule (typically assumed to be 1.35 nm2), Co and Ce are the initial and equilibrium concentrations of MB, V is the volume of MB solution, MMB is the relative molecular mass of MB, and ms is the mass of the sample
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