Spatial separation of photo-generated carriers in g-C3N4/MnO2/Pt with enhanced H2 evolution and organic pollutant control

Controllable Anchoring of Graphitic Carbon Nitride on MnO2 Nanoarchitectures for Oxygen Evolution Electrocatalysis

“…For composite materials, Mn 2p and Mn 3s energy positions underwent a red shift in comparison to MnO 2 (−0.2 eV for MnO 2 –M-180 and −0.4 eV for MnO 2 –CM-45; Tables S3 and S4). This phenomenon, in accordance with previously reported data for MnO 2 /g-CN materials, ,,,, confirmed that g-CN and MnO 2 were directly coupled in the fabricated composite systems, and that a built-in electric field was formed at the g-CN/MnO 2 interface . The occurrence of the latter promoted a g-CN → MnO 2 electron transfer, a phenomenon which, on the basis of the measured BE shifts, turned out to be more marked for MnO 2 –CM-45 than for MnO 2 –M-180.…”

“…Water splitting, eventually activated by largely available and intrinsically renewable solar light, has been hailed as an extremely attractive route for the carbon-neutral production of green hydrogen (H 2 ), paving the way to a new sustainable energy infrastructure in the near future. – In general, H 2 O electrolysis involves the hydrogen evolution reaction at the cathode of an electrochemical cell and the oxygen evolution reaction (OER) at the anode, the latter being the overall process bottleneck due to its sluggish kinetics. ,– Since large-scale applications of the actual state-of-the-art OER catalysts based on RuO 2 and IrO 2 – are prevented by various issues, encompassing their high cost, insufficient long-term stability, and scarcity, ,,, numerous efforts are being dedicated to alternative eco-friendly electrocatalysts, highly required in the framework of improved sustainability. ,,,, …”

“…In this context, graphitic carbon nitride (g-CN), a polymeric metal-free semiconductor, has drawn an ever-growing attention. ,,– This remarkable interest can be traced back to its low cost, nontoxicity, flexible two-dimensional (2D) structure, chemical/thermal stability, tunable defectivity, and appropriate band gap to harvest vis radiation ( E G ≈ 2.7 eV). ,,– In spite of these advantages, g-CN suffers from low surface area, low electrical conductivity, limited active site availability, and fast recombination of photogenerated charge carriers. ,,,,,– Among the various routes adopted to improve g-CN performances, – ,,, the controlled construction of heterojunctions between g-CN and a suitable semiconducting partner can yield a more efficient harvesting of solar light and an improved separation of photoproduced electrons and holes. ,,,,– Amid the different candidates, MnO 2 , featuring environmental friendliness, earth abundance, and low cost, is an attractive choice, ,, thanks to the band structure matching with g-CN one and the narrower band gap ( E G ≈ 2.0 eV), enabling, in turn, to extend sunlight utilization. ,,,, …”

“…So far, MnO 2 + g-CN composites have been prepared by liquid-phase routes for applications as supercapacitors ,, and (photo)­catalysts for CO 2 reduction, , toxic product degradation, ,,,, H 2 generation, ,,,, and oxidation reactions of industrial interest. , In a different way, the available studies on MnO 2 /g-CN OER electrocatalysts ,, (or MnO 2 composites with C tubes/dots/fibers ,,,,, ) are more scarce. Furthermore, most of the available studies have focused on powdered systems, either as such ,,,,,,,,,, or mixed with binders/additives to yield pastes immobilized on supports, – ,,, whereas a primary requirement for real-world applications is the direct growth of active materials onto suitable substrates. ,,,, …”

Preparation of MnO2-Carbon Materials and Their Applications in Photocatalytic Water Treatment

“…Under the irradiation of xenon lamps, the ability of the composite material to degrade phenol is significantly increased, and it has good durability. Preparing the photocatalyst of the MnO 2 -carbon composites with low bandgap can make full use of solar energy and provide a sustainable green approach for photocatalytic water treatment, and its application potential needs to be further developed [ 208 , 209 , 210 , 211 , 212 ].…”