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• Ti 3 C 2 T x /TiO 2 -400 toward NIR light-driven N 2 photofixation was successfully developed by combining Ti 3 C 2 T x MXene with TiO 2. • The NH 3 production rate of Ti 3 C 2 T x /TiO 2 -400 reached 422 μmol g cat. –1 h–1 under full-spectrum in water without any sacrificial agents. • Superior activity was achieved for Ti 3 C 2 T x /TiO 2 -400 with the NH 3 production rate of 82 μmol g cat. –1 h–1 by applying 740-nm monochromatic light. • Plasmonic Ti 3 C 2 T x Mxene phase in Ti 3 C 2 T x /TiO 2 -400 enabled the harvesting of NIR light to generate hot electrons. • Oxygen vacancies in TiO 2 phase of Ti 3 C 2 T x /TiO 2 -400 served as the active centers to efficiently adsorb and activate N 2 molecules. Utilization of infrared (IR)/near-infrared (NIR) light paves an opportunity to improve the efficiency of N 2 photofixation under full-spectrum irradiation, but remains as a grand challenge. Herein, a highly active photocatalyst toward NIR light-driven N 2 photofixation was successfully developed by construction of plasmonic Ti 3 C 2 T x MXene and TiO 2 hybrid structures (Ti 3 C 2 T x /TiO 2 -400). Impressively, Ti 3 C 2 T x /TiO 2 -400 exhibited remarkable activity in N 2 photofixation under full-spectrum irradiation of Xenon lamp, attaining an NH 3 production rate of 422 μmol g cat. –1 h–1 without any sacrificial agents. More importantly, superior activity under NIR light was even achieved for Ti 3 C 2 T x /TiO 2 -400 with the NH 3 production rate up to 82 μmol g cat. –1 h–1 by applying 740-nm monochromatic light. Further mechanistic studies revealed that plasmonic Ti 3 C 2 T x Mxene phase in Ti 3 C 2 T x /TiO 2 -400 enabled the harvesting of NIR light. Moreover, oxygen vacancies in TiO 2 phase of Ti 3 C 2 T x /TiO 2 -400 served as the active centers to efficiently adsorb and activate N 2. [ABSTRACT FROM AUTHOR]

Solar-driven H 2 O 2 photosynthesis from inexhaustible seawater is promising for alleviating increasingly-serious energy/environmental crises. Herein, a new metal-free photothermal-assisted photocatalyst containing strong π-stacked polyfuran D-A couples is synthesized by employing 5-hydroxymethylfurfural as precursor, which enables the highly-efficient H 2 O 2 photosynthesis from seawater without any sacrificial agent. Its unique aromatic and quinoid furan alternating structure promotes the photogenerated charge transfer and the activation of oxygen molecules, thus remarkedly boosting H 2 O 2 production rate. Furthermore, its localized photothermal and "electron bridge" effects can enhance the kinetic process of this reaction and accelerate the charge transfer, respectively, resulting in a high H 2 O 2 yield of 1883.81 μmol g−1 h−1 with a high solar-to-chemical conversion efficiency of 0.48 % in seawater under simulated-sunlight irradiation. Impressively, it can achieve a high H 2 O 2 concentration of 1867.81 μmol L−1 in natural seawater in one day under natural-sunlight irradiation, representing the first successful application of metal-free polyfuran photocatalysts for the photothermal-assisted H 2 O 2 photosynthesis from natural seawater. [Display omitted] • Metal-free photocatalysts with π-stacked polyfuran couples are synthesized from HMF. • The unique aromatic and quinoid furan alternating structure can promote charge transfer. • Photothermal and electron bridge effect in HDPC can enhance the H 2 O 2 generation kinetics. • HDPC can achieve a high H 2 O 2 yield of 1867.81 μmol L−1 in one day under natural sunlight. [ABSTRACT FROM AUTHOR]