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Although the construction of heterojunction photocatalysts is a promising way to achieve outstanding photocatalytic activities, a 2D heterojunction which possesses strong chemical bonding and appropriate interfacial contact toward efficient artificial photosynthesis is still a challenge. Herein, 2D/2D Nb2O5/g‐C3N4 S‐scheme heterojunction photocatalysts are successfully fabricated by a convenient in situ calcination route derived from niobic acid/urea precursor for the gas–solid CO2 reduction reaction. Under simulated solar irradiation, the total yield of C1 products (CH4 and CO) obtained on the optimized sample NOCN‐5 are 6.7 times and 5.3 times that over pristine Nb2O5 and g–C3N4 nanosheets, respectively, without sacrificial agent or cocatalysts. The enhanced performances of CO2 photoreduction might be attributed to the unique Nb─O─C chemical bonds induced charge transfer bridge, face‐to‐face contact, and the efficient S‐scheme transfer path of photoinduced electron–hole pairs, which is confirmed by in situ illuminated X‐ray photoelectron spectroscopy and density functional theory calculation. This work will provide a promising strategy for constructing S‐scheme heterojunction systems for efficient artificial photosynthesis reactions toward carbon neutrality.

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Unveiling the charge separation and transfer pathways and exploring low‐cost and durable heterojunction photocatalysts are still two key challenges in achieving high‐efficient solar fuel generation from low‐concentration carbon dioxide. Herein, the layered In2S3‐modified Nb2O5 hybrid nanofiber photocatalysts with core–shell structures for efficient low‐concentration CO2 hydrogenation are constructed. The as‐prepared binary S‐scheme photocatalysts show excellent CO generation of 60.36 μmol g−1 h−1, which is 5.6 and 3.8 times higher than that of Nb2O5 and In2S3, which not only exhibits the CO generation in low‐concentration CO2 but also is superior to most photocatalysts without sacrificial agents or cocatalysts. In situ illuminated X‐ray photoelectron spectroscopy analysis indicates the S‐scheme charge transfer pathways formed due to the unmatched Fermi level, creating an internal electric field at the core/shell interface, driving the separation of the photoexcited charge carriers. This work will provide a promising strategy for constructing nanofiber‐based heterojunction photocatalysts for efficient low‐concentration CO2 hydrogenation reactions.

Exploring and designing highly efficient solar‐driven CO2 overall splitting photocatalysts toward carbon neutrality is still challenging. Herein, a novel core–shell Ta2O5/ZnIn2S4 heterojunction photocatalyst is fabricated where ZnIn2S4 nanosheets are deposited on mesoporous Ta2O5 nanofibers via electrospinning and hydrothermal methods. In situ‐illuminated X‐ray photoelectron spectra analysis and density functional theory calculation imply that the photoelectrons in ZnIn2S4 can transfer to Ta2O5 though a 2D/1D interface, accelerating the separation of photogenerated electron–hole pairs driven by the built‐in electric field under illumination, coupling the S‐scheme charge transfer mechanism. As a result, the total yield of CO2 overall splitting (including CO and CH4) over ZISTO0.1 is about 4.1 and 5.74 times that of pristine Ta2O5 nanofibers and ZnIn2S4 nanosheets, respectively. This work may pave a promising strategy of designing heterojunction photocatalysts with S‐scheme pathways toward solar fuel generation.