H2O2 has a wide range of uses as an oxidant and is also utilized as a high density and environmentally friendly fuel. In this study, crystalline g-C3N4 was modified with K+, Ni and N-doped carbon by thermal-polymerization of Ni2+-anchored and polyvinyl pyrrolidone-encapsulated melamine-cyanuric acid supramolecules, followed by re-calcination in a KCl–LiCl mixture. The obtained strip-like g-C3N4 nanocrystals exhibited high charge separation efficiency and good light absorption capability. Density-functional theory calculations confirmed that the orbital hybridization of Ni–N atoms enabled the formation of charge-transfer channels, which can capture electrons, achieve enhanced oxygen adsorption and reduction via a two-electron pathway. Under the synergistic effects of K+, Ni and N-doped carbon dopants and crystallinity, the obtained sample exhibited high photocatalytic H2O2 yields of 79.6 μM in O2-saturated pure water, which was 10-fold higher than the yield using pristine g-C3N4. This work provides a novel design for production of highly efficient photocatalysts for H2O2 production.
Methanol is a suitable raw material for in situ hydrogen generation by steam reforming that enables the safe storage and transportation of hydrogen. Pt-based catalysts have been considered promising and effective for methanol steam reforming but suffer from deactivation by metal sintering. In this study, we developed an efficient K-modified Pt catalyst confined within silicate-1 zeolite with a high activity and unprecedented stability for methanol steam reforming. Owing to the confinement effect, the K-promoted Pt@S-1 catalyst remained stable for more than 50 h. The combination of TPSR-MS and DFT calculations revealed that the Pt-K@S-1 catalyst exhibited a synergistic effect between the Pt 0 and Pt δ+ species. The cleavage of the O–H bond in CH 3 OH was activated over Pt 0 sites to produce HCOOCH 3 , whereas Pt δ+ sites promoted the hydrolysis of HCOOCH 3 to HCOOH and ultimately CO 2 and H 2 , thus suppressing the formation of CO and boosting H 2 production.
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