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Photoreforming of biomass into hydrogen, biofuels, and chemicals is highly desired, yet this field of research is still in its infancy. Developing an efficient, novel, and environmentally friendly photocatalyst is key to achieving these goals. To date, the nonmetallic and eco‐friendly material carbon nitride has found many uses in reactions such as water splitting, CO2 reduction, N2 fixation, and biorefinery, owing to its outstanding photocatalytic activity. However, a narrow light absorption range and fast charge recombination are often encountered in the pristine carbon nitride photocatalytic system, which resulted in unsatisfying photocatalytic activity. To improve the photocatalytic performance of pure carbon nitride in biomass reforming, modification is needed. In this Review, the design and preparation of functional carbon nitride, as well as its photocatalytic properties for the synthesis of hydrogen, biofuels, and chemicals through biomass reforming, are discussed alongside potential avenues for its future development. [ABSTRACT FROM AUTHOR]

• The FG- s -PVA@CNNS has fast charge separation rate and low resistance. • The FG- s -PVA@CNNS shows excellent performance for lactic acid synthesis. • The ·O 2 - played a primary role for lactic acid synthesis. • Good yield of lactic acid was observed from 1000-fold scale-up experiment. The development of hydrogel-based photocatalysts with three-dimensional ordered porous structure, fast charge separation, and low resistance is significantly in photocatalytic biorefinery but nonetheless poses certain challenges. Herein, we introduced a novel strategy to prepare "Fish gill"-shaped hydrogel-based photocatalysts via freezing-induced encapsulation of ultra-thin carbon nitride nanosheets into a three-dimensional ordered porous polyvinyl alcohol matrix (name as FG- s -PVA@CNNS x). The encapsulation of CNNS in FG- s -PVA@CNNS 3 posed no effects on the absorption of visible light but accelerated the transfer/migration of photo-induced charge and reduced the resistance. For photocatalysis, the ordered porous structure of FG- s -PVA@CNNS 3 proved to be conducive to the reactants adsorption and mass transfer while the lactic acid yield achieved 92.6%. FG- s -PVA@CNNS 3 exhibited excellent stability and reusability, in which the yield of the 10th cycle well reached 95.6% of its first cycle. FG- s -PVA@CNNS 3 also displayed exceptional universality wherein the lactic acid yields were 92.6% (glucose), 89.1% (fructose), 88.6% (mannose), 56.0% (rhamnose), 71.1% (arabinose), and 70.9% (xylose). In addition, the effects of various oxidative species on the photocatalytic reaction were systematically discussed, among which ·O 2 - played a pertinent role. Overall, the construct of hydrogel-based photocatalysts and their application provide a strategy for photocatalytic biorefinery. [Display omitted]. [ABSTRACT FROM AUTHOR]

Photocatalysis provides a promising opportunity for selective oxidation of biomass to high-value chemicals under mild conditions. The key to realize this transformation is to design a cost-effective and environmentally friendly photocatalyst. Here, we report the preparation of a carbon nitride photocatalyst with controllable carbon/nitride (C/N) ratio and its application in the selective photocatalytic synthesis of lactic acid from biomass-derived monosaccharides. Reasonable C/N ratio in the catalyst can significantly enhance the visible light absorption range and accelerate the mobility of photogenerated carriers. The obtained photocatalyst exhibited excellent photocatalytic activity, yielding 76.8% lactic acid. All of the h+,·O 2 -,·OH and 1O 2 are beneficial for lactic acid production, and the·O 2 - plays a major role. Furthermore, the photocatalyst exhibited excellent reusability and universality. The 1000-fold scale-up experiments indicated that the system has potential for industrial production of lactic acid. Therefore, the present work offers a promising example for photocatalytic reforming of biomass. Reasonable regulation of carbon/nitride ratio in carbon nitride for efficient photocatalytic reforming of biomass-derived feedstocks to lactic acid [Display omitted] • A photocatalyst (CC 1 @mCN 10) with controllable carbon/nitride ratio was prepared. • Reasonable C/N ratio in the catalyst enhance the visible light absorption range. • The·O 2 - plays a major role on the synthesis of lactic acid. • The CC 1 @mCN 10 shows excellent stability and reusability. [ABSTRACT FROM AUTHOR]