Fast Interfacial Carrier Dynamics Modulated by Bidirectional Charge Transport Channels in ZnIn2 S4 -based Composite Photoanodes Probed by Scanning Photoelectrochemical Microscopy

Regulating Asymmetric Charge Distribution in Cu2MoS4 Nanosheets for Enhanced Photocatalytic CO2 Reduction

Photocatalytic reduction of CO2 to high-value-added chemicals represents a promising strategy for effective CO2 utilization, and rationally regulating the electronic structure of the catalyst is the key to enhancing photocatalytic performance. Herein, it is demonstrated that in situ doping of atomic indium into the lattice of the Cu2MoS4 catalyst results in remarkable enhancements in photocatalytic CO2 reduction performance. A record gas product yield of 104.1 µmol·g-1·h-1 is achieved under visible light irradiation (>420 nm), accompanied by a generation rate of 35.3 µmol·g-1·h-1 for ethylene. Detailed experimental analyses and density functional theory (DFT) calculations reveal that the low electronegativity of indium atoms induces asymmetric charge redistribution near the doping sites. This effect facilitates the adsorption and dissociation of CO2 molecules at the charge-enriched Mo sites, as well as the subsequent generation of key intermediates (*COCOH) toward ethylene formation. This work advances understanding of the potential mechanism between the electronic structure of the active site and photocatalytic performance, providing valuable insights into fabricating advanced materials for CO2 conversion into solar fuels.

Aptamer-Induced Spatially Confined Electron Donors Enable Bi2S3/ZnIn2S4 Heterostructures for Attomolar Photoelectrochemical Detection of Antibiotic Resistance Genes

Despite the fact that the exploration of novel materials with excellent photoelectrochemical (PEC) performance is the sought-after objective for its detection of low abundance targets, the introduction of electron donors in a rational and efficient manner to further boost the PEC signals is still desirable. In this work, highly efficient PEC materials Bi2S3/ZnIn2S4 (BZ) heterojunctions were synthesized, and a strategy of aptamer-induced spatially confined electron donors (ASED) was, for the first time, proposed for highly enhanced and stable photocurrent generation. With dopamine (DA) or ascorbic acid (AA) as the electron donor model, ∼ 22-fold PEC signal enhancement could be obtained in the system using the ASED strategy. Furthermore, we established a newly updated PEC biosensor for antibiotic resistance genes based on the BZ materials and ASED strategy by ingeniously incorporating catalytic hairpin assembly (CHA) and DNAzyme cleavage reaction. It was demonstrated that our proposed biosensor exhibited an outstanding linear response to concentration variations from 0.1 fM to 1.0 nM and achieved a detection limit as low as 3.24 aM, without the need for additional electron donors. This strategy significantly enhances the analytical performance by in situ aptamer-promoted spatially confined electron donors toward simple, efficient, and enhanced PEC biosensors, which may shed light on biorecognition of electron donors based smart biosensing with broad applications.

Synergistic Enhancement of PEC Activity in Heterojunction Assisted by Oxygen Vacancies and Ferroelectric Polarization at Zero Bias: Mechanism Study and Achievement of Ultrasensitive Detection

The utilization of ferroelectric polarization-assisted photoelectrochemical (PEC) systems holds huge promise for solving the issue of high recombination of photogenerated electron-hole pairs. Monitoring their intricate charge-transfer process can offer profound insights into the advancement of highly active photoelectrodes. In this work, the hydrothermally synthesized titanium dioxide nanorod arrays (TiO2 NRAs) are subjected to in situ etching to introduce oxygen vacancies (Ov), and subsequently loaded with barium titanate (BaTiO3, BTO) nanoparticles to form a ferroelectric polarization effect-assisted type-II heterojunction. The resulting Ov-TiO2/BTO demonstrates an ultrahigh photocurrent of 102 μA and outstanding stability over 7200 s, far surpassing majority of recently reported PEC photoanodes operating at a bias voltage of 0 V (vs Ag/AgCl). Notably, the photoinduced charge transfer in ferroelectric Ov-TiO2/BTO was monitored at the microscale by advanced scanning photoelectrochemical microscopy (SPECM). As a showcase, the aptamer-coupled self-powered PEC biosensor for kanamycin presents excellent sensitivity and good anti-interference ability. This study not only elucidates the intrinsic mechanism of the synergistic amplification of photoelectric signals by oxygen vacancies and ferroelectric heterojunctions but also provides a reliable platform for the ultrasensitive detection of biological molecules.

Se-S bonded non-metal elementary substance heterojunction activating photoelectrochemical water splitting

Non-metal elements are often merely regarded as electronic modulators, yet their intrinsic characteristics are frequently overlooked. Indeed, non-metal elements possess notable advantages in high-abundance, excellent hydrogen adsorption and the ability of active sites to be inversely activated, rendering them potential photoelectrochemical (PEC) materials. However, weak non-metal interbinding, susceptibility to photocorrosion, and high photogenerated carrier recombination rates hinder their practical applications. Herein, for the first time, we report a novel non-metal elementary substance heterojunction Se/S based on interfacial bonding engineering strategy. Atomic-level tight coupling of sulfonyl-rich sulfur quantum dots (SQDs) with selenium microtube arrays (Se-MTAs) enhances the structural stability of Se/S and introduces crucial Se-S heterointerfacial bonds, which not only endow Se/S with robust internal electronic interactions, but also provide high-speed channels for charge separation via unique bridging. Consequently, Se/S achieves optimal photocurrent density of 3.91 mA cm-2 at 0 VRHE, accompanied by long-term stability over 24 h. It is the highest value reported to date for Se-based photocathodes without co-catalyst and outperforms most metal-selenide-based photoelectrodes. Furthermore, the direct Z-scheme charge transport mechanism is exposed by in-depth spectroscopic analyses. Our work fills the gap in application of non-metal elementary substance heterojunction for PEC, poised for potential expansion into other new-energy devices.

Regulating the Layer Stacking Configuration of CTF-TiO2 Heterostructure for Improving the Photocatalytic CO2 Reduction

Herein, covalent triazine frameworks in eclipsed AA and staggered AB stacking modes are respectively used for the in-situ growth of TiO2, and two heterostructures are obtained. Due to the highly organized stacking of the molecular layer in CTF-AA that strengthens the interlayer interaction, the light absorption and carrier migration of CTF-AA/TiO2 are both enhanced in comparison to those of its component or CTF-AB/TiO2. Correspondently, the photocatalytic CO2 reduction reaction (CO2RR) of CTF-AA/TiO2 proffers 9.19 μmol·g-1·h-1 CH4 and 2.32 μmol·g-1·h-1 CO production, about 9.2 and 4.3 times greater than that of pristine TiO2, respectively. Even though the innate photoresponse of the triazine unit endows CTF-AB/TiO2 with augmented light capturing, its photocatalytic CO2 conversion is relatively insignificant. According to the analyses of the planar-averaged electron density difference and Bader charge, the unproductive CO2 efficiency might be due to the insufficient interfacial electron transfer from TiO2 to CTF-AB. Given that the ΔG (-3.22 eV) of CHO intermediate generation is lower than that of CO desorption (-1.23 eV), the reaction tends to further generate CH4 other than yielding CO. This study could shed fresh light over the reasonable design of effective photocatalytic heterostructures.

Amorphizing MnIn2S4 Atomic Layers Create an Asymmetrical InO1S5 Polarization Plane for Photocatalytic Ammonia Synthesis and CO2 Reduction

Building a polarization center is an effective avenue to boost charge separation and molecular activation in photocatalysis. However, a limited number of polarization centers are usually created. Here, a polarization plane based on two-dimensional (2D) atomic layers is designed to maximize the surface polarization centers. The Mn in a 2D crystal lattice is etched from the MnIn2S4 atomic layers to build a consecutive symmetry-breaking structure of isolated InO1S5 sites. More charges aggregate around O, making the isolated InO1S5 sites highly polarized. Due to the formation of the InO1S5 polarization plane, an enormous polarized electric field is formed perpendicular to the 2D atomic layers and the carrier lifetime can be prolonged from 93.2 ps in MnIn2S4 to 1130 ps in amorphous MnxIn2Sy. Meantime, the formed large charge density gradient favors coupling and activation of small molecules. Benefiting from these features, a good NH3 photosynthesis performance (515.8 μmol g-1 h-1) can be realized over amorphous MnxIn2Sy, roughly 2.5 and 48.9 times higher than those of MnIn2S4 atomic layers and bulk MnIn2S4, respectively. The apparent quantum yields reach 5.4 and 3.3% at 380 and 400 nm, respectively. Meanwhile, a greatly improved CO2 reduction activity is also achieved over MnxIn2Sy. This strategy provides an accessible pathway for designing an asymmetrical polarization plane to motivate photocatalysis optimization.

Ultrasound Induces Local Disorder of FeOOH on CdIn2S4 Photoanode for High Efficiency Photoelectrochemical Water Oxidation

The regulation of the crystal structure of oxygen evolution cocatalyst (OEC) is a promising strategy for enhancing the photoelectrochemical efficiency of photoanodes. However, the prevailing regulating approach typically requires a multistep procedure, presenting a significant challenge for maintaining the structural integrity and performance of the photoanode. Herein, FeOOH with a local disordered structure is directly grown on a CdIn2S4 (CIS) photoanode via a simple and mild sonochemical approach. By modulating the localized supersaturation of Ni ions, ultrasonic cavitation induces Ni ions to participate in the nucleation and growth of FeOOH clusters to cause local disorder of FeOOH. Consequently, the local disordered FeOOH facilitates the exposure of additional active sites, boosting OER kinetics and extending charge carrier lifetimes. Finally, the optimal photoanode reaches 4.52 mA cm-2 at 1.23 VRHE, and the onset potential shifts negatively by 330 mV, exhibiting excellent performance compared with that of other metal sulfide-based photoelectrodes reported thus far. This work provides a mild and controllable sonochemical method for regulating the phase structure of OECs to construct high-performance photoanodes.