The reasonable construction of heterojunction photocatalysts with clear nanostructures and a good interface contact especially the one-dimensional/two-dimensional (1D/2D) composite heterojunction with unique morphology is considered one of the most effective strategies for designing highly efficient photocatalysts. Herein, a series of the 1D β-keto-enamine-based covalent organic framework (COF)/2D g-C3N4 composite materials COF–CN (1:x; where 1:x represents the mass ratio of COF and g-C3N4, x = 2.5, 5, 10, 15, 20) is prepared through the in situ reaction of 2,4,6-triformylphloroglucinol (Tp) and benzidine (BD) in stripped g-C3N4 suspension. A series of characterizations, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), have verified their 1D/2D heterojunction structure. With the introduction of 1D COF nanobelts, the absorption of the composite is largely extended to 560 nm. Photocatalytic experiments reveal that the composite COF/CN shows evidently superior photocatalytic performance than individual COF and g-C3N4. The optimized COF–CN (1:10) exhibits a H2 production rate of 12.8 mmol g–1·h–1 under visible-light (λ ≥ 420 nm) irradiation, which is about 62 and 284 times higher than those of COF and g-C3N4, respectively. The apparent quantum efficiency (AQE) of COF–CN (1:10) is about 15.09% under 500 nm light irradiation, which is one of the highest among previous COF- or g-C3N4-based materials. This work provides important strategies for designing and constructing high-efficiency heterojunction photocatalysts with multidimensional features.

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The development of a new electrolytic water hydrogen production coupling system is the key to realize efficient and low-cost hydrogen production and promote its practical application. Herein, a green and efficient electrocatalytic biomass to formic acid (FA) coupled hydrogen production system has been developed. In such a system, carbohydrates such as glucose are oxidized to FA using polyoxometalates (POMs) as the redox anolyte, while H 2 is evolved continuously at the cathode. Among them, the yield of glucose to FA is as high as 62.5 %, and FA is the only liquid product. Furthermore, the system requires only 1.22 V to drive a current density of 50 mA cm À 2 , and the Faraday efficiency of hydrogen production is close to 100 %. Its electrical consumption is only 2.9 kWh Nm À 3 (H 2 ), which is only 69 % of that of traditional electrolytic water. This work opens up a promising direction for low-cost hydrogen production coupled with efficient biomass conversion.

Constructing bulk defects and doping are feasible ways to essentially narrow the band gap and improve the light absorption of photocatalysts. Herein, inspired by bread foaming, the foaming agent azoformamide or azodicarbonamide (AC) was introduced during the thermal polymerization of urea. In the polymerization process, a large number of bubbles produced by AC decomposition seriously interfered with the polymerization of urea, resulting in the breaking of the hydrogen bonds and van der Waals interaction in carbon nitride, distortion of its structure, and partial oxidation, thus forming a series of porous carbon nitrides U/AC x (x is the ratio of AC to urea; where x = 0.25, 0.5, and 1) with bulk N defects and O doping. Its band gap was reduced to 1.91 eV and the absorption band edge was greatly extended to 650 nm. The optimal U/AC 0.5 exhibits the highest visible light photocatalytic hydrogen production rate of about 44.7 μmol•h −1 (10 mg catalysts) and shows superior photocatalytic performance for the oxidation of diphenylhydrazine to azobenzene, with conversion and selectivity of almost 100%, and is one of the most active defective carbon nitrides, especially under long-wavelength (λ ≥ 550 nm) light irradiation. It paves the way for the design of highly efficient and wide-spectral-response photocatalysts.

Tunable CoxNi1−x/Al2O3 nanocatalysts have been prepared and used for the efficient tandem catalytic dehydrogenation of ammonia borane and hydrogenation of nitroaromatics.