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Photocatalytic overall water splitting (OWS) is an appealing strategy to convert solar energy and produce hydrogen fuel. NiTiO3 (NTO) is an earth‐abundant material, which is studied as a robust photocatalyst with broad absorptance of sunlight spectrum, ranging from ultraviolet to infrared regions. Herein, by a rational design of an NTO‐based photocatalytic system, the activity for photocatalytic OWS is realized under both ultraviolet and visible light illuminations, and H2 and O2 evolution is achieved within the stoichiometric ratio of 2:1. Specifically, Gallium is doped into the NTO crystal to activate the material for photocatalytic OWS by improving photoexcited charge migration. Meanwhile, Co and Pt species are screened out as the oxygen evolution and hydrogen evolution co‐catalysts, respectively. Theoretical stimulations, steady state experiments, and operando characterizations are acquired to investigate the OWS performance. This research paves the pathway to apply this small‐bandgap photocatalyst for OWS by maximizing the solar energy harvesting. [ABSTRACT FROM AUTHOR]

The visible‐light‐driven photocatalytic CO2 reduction is one appealing approach to simultaneously mitigate the energy crisis and environmental issues. It is highly desirable but challenging to selectively and efficiently convert CO2 into desirable products. Herein, a covalent organic framework hosting metalloporphyrin‐based carbon dots (M‐PCD@TD‐COF, M = Ni, Co, and Fe) is first presented, which serves as heterogeneous catalysts for CO2 photoreduction. M‐PCD@TD‐COF not only enriches available COF‐based catalytic materials, but also provides suitable environment for CO2 adsorption and activation on metalloporphyrin‐based carbon dots. The advantages of the host environment in COFs are highlighted by the satisfactory catalytic activity and remarkable selectivity of CO2‐to‐CO conversion over H2 generation up to 98%. The photocatalytic system is effective for both pure CO2 and the simulated flue gas. This work provides new protocols for the rational design of COF‐based heterogeneous catalysts for selective CO2 photoreduction. [ABSTRACT FROM AUTHOR]

Polymeric semiconductors are emerging as a kind of competitive photocatalysts for hydrogen evolution due to their well-tunable structures, versatile functionalization, and low-cost processibility. In this work, a series of conjugated porous polymers with substantial cyano-substituted fully sp2-carbon frameworks are efficiently synthesized by using electron-deficient tricyanomesitylene as a key building block to promote an organic base-catalyzed Knoevenagel condensation with various aldehyde-substituted arenes. The resulting porous polymers feature donor-acceptor structures with π-extended conjugation, rendering them with distinct semiconducting properties. They possess hierarchically porous structures, nanoscale morphologies, and intriguing wettability. These promising physical characters, finely tailorable by varying the arene units, are essentially relevant to the abundant cynao substituents over the whole frameworks. The as-prepared porous polymers exhibit excellent visible-light-driven photocatalytic activity for water-splitting hydrogen evolution with apparent quantum yield up to 2.0% at 420 nm or 1.9% at 470 nm, among the highest values yet reported for porous polymer-based photocatalysts, also representing the first example of such kinds of catalysts formed through a metal-free-catalyzed carbon-carbon coupling reaction. [ABSTRACT FROM AUTHOR]