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The efficient coupling of light absorbers with catalysts is the most critical step in the multielectron transfer process for CO2 conversion. Here a heterogenized photoconversion system consisting o...

Utilizing solar energy as a sustainable means of controlling the nitrogen pollutant is proposed. The photochemical conversion of nitrate (NO3−) to dinitrogen (N2) without using chemical reductants is an ideal solution but difficult to be realized. Here we demonstrate a successful case of solar denitrification (with 0.1–10 mM nitrate) coupled with in situ water splitting (without chemical reductants) by developing a ternary composite photocatalyst composed of TiO2, Cu–Pd bimetals, and reduced graphene oxide (rGO) (Cu–Pd/rGO/TiO2). Direct transformation of NO3− to N2 occurs on Cu–Pd/rGO/TiO2via using in situ H2 generated from water splitting in a broader pH range with achieving near 100% conversion and selectivity to N2 while it is not possible at all with rGO/TiO2 and Cu–Pd/TiO2. The unique activity is ascribed to the synergic action of Cu as a co-catalyst for nitrate-to-nitrite conversion, Pd for nitrite-to-dinitrogen conversion, and rGO for the enhanced charge separation/transfer and H2 production. The combined roles of Cu–Pd and rGO in retarding the charge recombination and accelerating the electron transfer from TiO2 to NO3− are confirmed by monitoring the time-resolved photoluminescence and slurry-type photocurrent generation, respectively. The in situ water splitting on Cu–Pd/rGO/TiO2 was confirmed by the concurrent H2 and O2 evolution and the in situ generated H2 was immediately consumed in the presence of nitrate. The introduction of rGO enabled the denitrification even under visible light (up to 450 nm) and the apparent quantum yield (AQY) of N2 production reached a maximum of 4.9% at 320 nm. The proposed composite photocatalytic system realizes the selective solar conversion for chemical reductant-free denitrification (nitrate to N2) by coupling nitrate reduction and water oxidation.

Next-generation electrocatalysts with smart integrated designs, maximizing the chemical cascade synergy for sustainable hydrogen production, are needed to address the urgent environmental threats, but scalable synthesis of precisely architectured nanohybrids rendering a few-nanometer interfacial controllability to augment the catalytic reactivity and operational stability is a major bottleneck. Herein, by inventing a surface-confined lateral growth of nanometer-thin and nanoporous two-dimensional (2D)-Pt on NiFe-LDH nanosheets, a highly reactive 2D-2D interfacially integrated nanoplatform is synthesized for an alkaline hydrogen evolution reaction (HER) which not only extracts high Pt-atomic utilization efficiency but also synergistically accelerates the water dissociation and hydrogen generation cascade on the colocalized Pt/M(OH)

The development of efficient and yet economic photocatalysts that can utilize solar light is crucial for the sustainable future. We report a simple approach to introduce a bidentate type of metal coordination site in polymeric carbon nitride (PCN) by an in situ keto–enol cyclization route of acetylacetone and urea to incorporate a metal chelating pyrimidine derivative into the molecular framework of PCN. The resulting new metal coordination sites provide both N- and O-complexing ligands unlike the unmodified PCN that has N-ligands only. As a proof-of-concept experiment, we introduced Al3+ ions into these coordination sites, which induced significant enhancements in visible light photocatalytic activities for organic pollutant degradation and H2 evolution as compared to those of bulk PCN and the conventional “nitrogen pot” metal-coordinated PCN. The optimized Al loading was as low as 0.32 wt %. The photocatalytic activities sensitively depended on the Al incorporation, and the Al-incorporated sample demons...

Single-step green synthesis of zinc blende ZnSe quantum dots (QDs) is performed using sodium selenide and zinc stearate. The present method is non-toxic and is considered reasonably green route where stearate ions released during the reaction act as surfactant. The size quantisation effect is revealed by blue shifted absorption bands with a band-gap energy of ~2.9 eV with respect to bulk ZnSe band-gap of 2.7 eV. Photoluminescence measurement with FWHM