A series of linear conjugated organoborane oligomers are synthesized here by introducing electron-deficient borole units to the well-explored thiophene unit of variable length. It is found that the photophysical properties, particularly the band structures of products, alter regularly with the extension of thiophene. Interestingly, such oligomers exhibit high activity for photocatalytic hydrogen evolution under visible light (λ > 420 nm), outperforming most of the reported linear polymers. The enhanced performance is possibly attributed to the strong electron-accepting nature of the borole group, as well as the good electron donor and light-harvesting properties of the thiophene group. The combination of these two units facilitates charge separation of oligomers, thus allowing the participation of as many photogenerated charge carriers as possible in the desired water reduction reaction. The results indicate the success of our strategy and the importance of rational molecular design for developing conjugated (oligo)polymers for efficient photocatalytic hydrogen evolution.

Poor charge separation is the main factor that limits the photocatalytic hydrogen generation efficiency of organic conjugated polymers. In this work, a series of linear donor–acceptor (D–A) type oligomers are synthesized by a palladium‐catalyzed Sonogashira–Hagihara coupling of electron‐deficient diborane unit and different dihalide substitution sulfur functionalized monomers. Such diborane‐based A unit exerts great impact on the resulting oligomers, including distinct semiconductor characters with isolated lowest unoccupied molecular orbital (LUMO) orbits locating in diborane‐containing fragment, and elevated LUMO level higher than water reduction potential. Relative to A‐A type counterpart, the enhanced dipole polarization effect in D–A oligomers facilitates separation of photogenerated charge carriers, as evidenced by notably prolonged electron lifetime. Owing to π–π stacking of rigid backbone, the oligomers can aggregate into an interesting 2D semicrystalline nanosheet (≈2.74 nm), which is rarely reported in linear polymeric photocatalysts prepared by similar carbon–carbon coupling reaction. Despite low surface area (30.3 m2 g−1), such ultrathin nanosheet D–A oligomer offers outstanding visible light (λ > 420 nm) hydrogen evolution rate of 833 µmol g−1 h−1, 14 times greater than its A‐A analogue (61 µmol g−1 h−1). The study highlights the great potential of using boron element to construct D–A type oligomers for efficient photocatalytic hydrogen generation.

Oxygen vacancy engineering is effective for improving the photoelectrochemical (PEC) performance of electrodes. However, such a protocol has not yet shown impressive success for ZnO photoanodes due to the unstable nature of ZnO under a reducing atmosphere. In this work, an electrochemical method is explored to create oxygen vacancies in ZnO with a controllable concentration. Unlike the successful example of other materials with chemical treatment, such a mild electrochemical method seems unable to evidently extend the working spectrum of ZnO by generating isolated trap states or upshifting the conduction band edge, but it dramatically improves the light absorption in the UV region. Importantly, we find that the created oxygen vacancies act as water oxidation intermediate species facilitating charge transfer rather than recombination sites. The origin of this merit is explained by the lowered overpotential for water oxidation on the ZnO surface. Moreover, it is also found that a balance among the density of oxygen vacancy, charge separation, and charge transfer is required to maximize the efficiency of ZnO by giving enough surface reactive sites and efficient bulk charge separation. The optimized ZnO achieves a photocurrent density of 1.2 mA cm–2 at 1.23 V vs reversible hydrogen electrode, 3.0 times greater than that of the pristine sample (0.4 mA cm–2). Without doubt, the electrochemical treatment affords a new avenue for enhancing the PEC performance of ZnO and may hold huge potential applications in other semiconductors for large-scale manufacturing.

Tl + has long been known for its high toxicity and can cause various illnesses, but its sensing is seldom explored compared with other heavy metal ions. Here, we report for the first time a photoelectrochemical (PEC) sensor for Tl + with a highly porous In 2 S 3 anode which is assembled by ultrathin nanosheets. The photoanode shows a notable peak in photocurrent J−V curve at −0.65 V vs Ag/AgCl, resulting from oxidation of rich sulfide (surface states) in the surface of In 2 S 3 by photogenerated holes. Upon combination of surface sulfide with Tl + , such a peak can be evidently quenched as a function of the concentration of Tl + . Therefore, a PEC sensor based on the unique mechanism of surface state passivation is thus developed. Benefiting from the sensitivity of surface states to guest materials, the proposed system offers a detection limit of 0.36 μM. Unexpectedly, the sensor also exhibits higher selectivity to Tl + than to other metal ions, possibly due to the high affinity between Tl + and sulfide, as well as the applied low bias potential that avoids direct oxidation of analytes. The successful application of such a mechanism in the detection of Tl + brings perspectives for the exploration and design of the PEC sensing system.

The intrinsic high charge recombination and narrow light absorption seriously affect the performance of g-C3N4 toward photocatalytic hydrogen generation. In this work, this problem is partially overcome by a dual-gas-phase treatment protocol, first ammonia and followed by phosphine annealing. Owing to facilitated contact between gas precursor and layered g-C3N4, the ammonia annealing created N vacancies provide cross-plane diffusion channels for efficient bulk charge separation and more active sites due to decreased aggregation. Despite the band gap broadening being accompanied by ammonia annealing, the introduction of a secondary impurity (P atom) in corner carbon sites narrows down the band gap to 2.56 eV. The combination of N defects (amine groups) and P dopants (carbon defects) allows capturing as many atomic Pt as possible as cocatalyst, with weakened binding energy between Pt and H atom by 0.42 V when compared to Pt–H binding in pristine g-C3N4. This leads to a low overpotential for materials to efficiently break energy barriers in the process of interfacial charge transfer. As a result, the target material beyond the one obtained by traditional solid or liquid doping delivers a hydrogen evolution rate up to 1959 μmol·h–1·g–1 under visible light (λ > 420 nm), nearly 8 times higher than that of pristine g-C3N4/Pt (250 μmol·h–1·g–1). The results demonstrate the success of our dual-gas-phase activation strategy and the importance of rational dual-defect engineering for improving the photocatalytic activity of layered materials, not limited to g-C3N4.