Three-layered nanoplates and amorphous/crystalline interface synergism boost CO2 photoreduction on bismuth oxychloride nanospheres.

Structural features like 3D nano-size, ultrathin thickness and amorphous/crystalline interfaces play crucial roles in regulating charge separation and active sites of photocatalysts. However, their co-occurrence in a single catalyst and exploitation in photocatalytic CO2 reduction (PCR) remains challenging. Herein, nano-sized bismuth oxychloride spheres (BiOCl-NS) confining three-layered nanoplates (∼2.2 nm ultrathin) and an amorphous/crystalline interface are exclusively developed via intrinsic engineering for an enhanced sacrificial-reagent-free PCR system. The results uncover a unique synergism wherein the three-layered nanoplates accelerate electron-hole separation, and the amorphous/crystalline interface exposes electron-localized active sites (Bi-Ovac-Bi). Consequently, BiOCl-NS exhibit efficient CO2 adsorption and activation with the lowering of rate-determining-step energy barriers, leading to remarkable CO production (102.72 µmol g-1 h-1) with high selectivity (>99%), stability (>30 h), and apparent quantum efficiency (0.51%), outperforming conventional counterparts. Our work provides a facile structural engineering approach for boosting PCR and offers distinct synergism for advancing diverse materials.

Rubidium Doped Cs2AgBiBr6 Hierarchical Microsphere for Enhanced Photocatalytic CO2 Reduction.

Halide perovskites have garnered significant attention for their unique optoelectronic properties in solar-to-fuel conversions. However, the efficiency of halide perovskites in the field of photocatalytic CO2 reduction is largely limited by serious charge recombination and a lack of efficient active sites. In this work, a rubidium (Rb) doped Cs2AgBiBr6 (Rb:CABB) hierarchical microsphere is developed for photocatalytic CO2 reduction. Experimental and theoretical analysis discloses that partially substituting Rb+ for Ag+ can effectively modulate the electronic structure of CABB, favoring charge separation and making adjacent Bi atoms an electron-rich active site. Further investigations indicated that Rb doping also reduces the energy barriers of the rate-determining step in CO2 reduction. As a result, Rb:CABB demonstrated an enhanced CO yield compared to its undoped counterpart. This work presents a promising approach to optimizing the electronic structures of photocatalysts and paving a new way for exploring halide perovskites for photocatalytic CO2 reduction.

Regulating the Active Sites of Cs2 AgBiCl6 by Doping for Efficient Coupling of Photocatalytic CO2 Reduction and Benzyl Alcohol Oxidation.

Halide perovskites exhibit outstanding optoelectronic properties, which make them an ideal choice for photocatalytic CO2 reduction and benzyl alcohol (BA) oxidation. Nevertheless, the simultaneous realization of the above redox coupling reactions on halide perovskites remains a great challenge, as it requires distinct catalytic sites for different target reactions. Herein, the catalytic sites of Cs2 AgBiCl6 (CABC) are regulated by doping Fe for efficient coupling of photocatalytic CO2 reduction and BA oxidation. The Fe-doped CABC (Fe: CABC) exhibits an enhanced visible-light response and effective charge separation. Experimental results and theoretical calculations reveal a synergistic interplay between Bi and Fe sites, where the Bi and Fe sites have lower activation energies toward CO2 reduction and BA oxidation. Further investigations demonstrate that electrons and holes prefer to accumulate at the Bi site and Fe site under light irradiation, respectively, which creates favorable conditions for facilitating CO2 reduction and BA oxidation. The resultant Fe: CABC achieves a high photocatalytic performance toward CO (18.5 µmol g-1  h-1 ) and BD (1.1 mmol g-1  h-1 ) generation, which surpasses most of the state-of-the-art halide photocatalysts. This work demonstrates a facile strategy for regulating the catalytic site for redox coupling reactions, which will pave a new way for designing halide perovskites for photocatalysis.

One-pot, ligand-free, room-temperature synthesis of Au/Pd/ZnO nanoclusters with ultra-low noble metal loading and synergistically improved photocatalytic performances.

Au/Pd/ZnO nanoclusters with ultra-low noble metal loadings were prepared by a one-step and ligand-free method at room temperature. HRTEM, ICP-MS, XPS, and elemental mapping analysis confirmed that the obtained Au/Pd/ZnO nanoclusters were composed of ZnO nanoclusters decorated with well-dispersed AuPd nanoparticles. Au/Pd/ZnO nanoclusters exhibited higher photocatalytic activity compared with those of pristine ZnO, Au/ZnO and Pd/ZnO. Moreover, the high catalytic activity of Au/Pd/ZnO nanoclusters could be maintained even after 5 cycles of photocatalytic reaction. A mechanism for the enhanced photocatalytic performance was also suggested, which was in light of the synergistic effects of the SPR effect from Au and the improved photogenerated charge carrier separation from Pd.

A CTAB-mediated antisolvent vapor route to shale-like Cs4PbBr6 microplates showing an eminent photoluminescence.

Compared with nanoscale quantum dots (QDs), the large-sized perovskite crystals not only possess better stability but also are convenient for application exploration. Herein, we develop a facile and efficient antisolvent vapor-assisted recrystallization approach for the synthesis of large-sized Cs4PbBr6 perovskite crystal microplates. In this method, for the first time, the shale-like Cs4PbBr6 microplates with lateral dimensions of hundreds of microns are fabricated by employing cetyltriethylammnonium bromide (CTAB) as a morphology-directing agent. FESEM, TEM, and AFM characterizations indicate that the as-obtained shale-like Cs4PbBr6 microplates are actually formed by 6-8 nm thick Cs4PbBr6 nanosheets with orientational stacking. Importantly, such highly crystalline Cs4PbBr6 microplates with shale-like morphology exhibit a narrow and intense green PL emission with a 59% PL quantum yield. Moreover, the planar structure of shale-like Cs4PbBr6 microplates makes it easy to form a preferred orientation on a substrate, which endow them with promising potential in optoelectronic devices such as lighting and displays.

The structures, water stabilities and photoluminescence properties of two types of iodocuprate(i)-based hybrids.

Although great progress has been made in hybrid iodocuprates(i) as lighting phosphors, the effects of aromatic and aliphatic structure directing agents (SDAs) on their water stability, structure and photoluminescence (PL) properties are still not clear. Herein, aromatic N-heterocyclic 1,2-di(4-pyridyl)ethylene (dpe), aliphatic N-heterocyclic 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu) and N-aminoethylpiperazine (app) were selected to be SDAs to construct two types of hybrid iodocuprates(i) via a facile in situ approach. Aromatic dpe-derived cations are successfully directed to form (Me2dpe)(CuI3) (1), (Me2dpe)n(Cu4I6)n (2), (Et2dpe)2(Cu6I10) (3), and (H2dpe)n(Cu2I4)n (4). Three of them contain unprecedented inorganic iodocuprate clusters or chains. The aliphatic N-heterocyclic dbu- and app-derivative cations are responsible for the formation of (Hdbu)n(Cu2I3)n (5) and (H3app)2(Cu2I6)·2I·2H2O (6), which contain a (Cu2I3)- chain and a (Cu2I6)4- binuclear cluster, respectively. For the first time, the influence mechanisms of the water stabilities of iodocuprate-based PL materials were disclosed, by analyzing the possible interactions between SDAs and water molecules. 1-2 are PL silent due to their "self-quenching effect". 3, 4 and5 exhibit bright red, orange and yellow solid-state PL emissions at room temperature respectively, originating from the charge transfer between inorganic iodocuprate species and organic N-heterocycles. The co-template approach leads to multiple charge transfers in 6, which features a tunable PL behavior from bluish green to white by varying the excitation light, and has a quantum yield up to 43% (the highest value among hybrid iodocuprates containing (Cu2I6)4- clusters). The comparative study not only helps us to rationally synthesize iodocuprate-based PL materials with enhanced performance, but also provides a new method to obtain wavelength-dependent PL materials.