Metal cocatalyst loading is one of the most widely explored strategies in promoting photocatalytic solar energy conversion. Engineering surface-active facets of metal cocatalyst and exploring how they modulate the reactivity is crucial for the further development of advanced photocatalysts. In this work, through controlled hybridization of two-dimensional (2D) TiO 2 nanosheets with well-designed Pd nanocube (Pd NC) with exposed {100} facet and Pd nano-octahedron (NO) with exposed {111} facet, we unravel the distinct crystal facet effect of Pd cocatalyst in promoting the selective hydrogenation of nitroarenes to amines of TiO 2 photocatalyst. The activity tests show that the Pd NO with {111} facet is a more efficient cocatalyst than the Pd NC with exposed {100} facet. The prepared TiO 2 -Pd NO composite displays a 900% enhancement of photocatalytic hydrogenation rate in comparison with bare TiO 2 , while the TiO 2 -Pd NC sample only shows a 200% photoactivity enhancement. Microscopic mechanism study discloses that the distinctive photoactivity improvement of Pd NO is ascribed to the concurrent modulation of the Schottky barrier height and enrichment of surface reactants: (i) the Pd NO with a lower Fermi level could result in steeper band bending of TiO 2 (i.e., higher Schottky barrier) than the Pd NC, which is more efficient in boosting interfacial separation and inhibiting the recombination of photoexcited charge pairs; and (ii) the {111} facet of Pd has higher nitroarenes adsorption ability and especially stronger hydrogen enrichment capability, thus accelerating the surface hydrogenation process and contributing to a higher reaction rate. This work emphasizes the rational facet control of cocatalysts for enhancing the photocatalytic hydrogenation performance.

Laser ablation in liquids (LAL) has emerged as a versatile approach for the synthesis of alloy particles and oxide nanomaterials. However, complex chemical reactions often take place during synthesis due to inevitable atomization and ionization of the target materials and decomposition/hydrolysis of solvent/solution molecules, making it difficult to understand the particle formation mechanisms. In this paper, a possible route for the formation of FeMn alloy nanoparticles as well as MnOx nanoparticles, ‐sheets, and ‐fibers by LAL is presented. The observed structural, compositional, and morphological variations are clarified by transmission electron microscopy (TEM). The studies suggest that a reaction between Mn atoms and Fe ions followed by surface oxidation result in nonstoichiometric synthesis of Fe‐rich FeMn@FeMn2O4 core–shell alloy particles. Interestingly, a phase transformation from Mn3O4 to Mn2O3 and finally to Ramsdellite γ‐MnO2 is accompanied by a morphology change from nanosheets to nanofibers in gradually increasing oxidizing environments. High‐resolution TEM images reveal that the particle‐attachment mechanism dominates the growth of different manganese oxides.

Pulsed laser melting in liquid (PLML) has emerged as a facile approach to synthesize submicron spheres (SMSs) for various applications. Typically lasers with long pulse durations in the nanosecond regime are used. However, recent findings show that during melting the energy absorbed by the particle will be dissipated promptly after laser-matter interaction following the temperature decrease within tens of nanoseconds and hence limiting the efficiency of longer pulse widths. Here, the feasibility to utilize a picosecond laser to synthesize Ge SMSs (200~1000 nm in diameter) is demonstrated by irradiating polydisperse Ge powders in water and isopropanol. Through analyzing the educt size dependent SMSs formation mechanism, we find that Ge powders (200~1000 nm) are directly transformed into SMSs during PLML via reshaping, while comparatively larger powders (1000~2000 nm) are split into daughter SMSs via liquid droplet bisection. Furthermore, the contribution of powders larger than 2000 nm and smaller than 200 nm to form SMSs is discussed. This work shows that compared to nanosecond lasers, picosecond lasers are also suitable to produce SMSs if the pulse duration is longer than the material electron-phonon coupling period to allow thermal relaxation.

The development of effective electrocatalysts for sustainable energy conversion and storage is highly desired, but still a considerable challenge due to the sluggish oxygen evolution reaction (OER). Herein, we report...

Photocatalytic H2 evolution coupled with organic transformation provides a new avenue to cooperatively produce clean fuels and fine chemicals, enabling a more efficient conversion of solar energy. Here, a novel two-dimensional (2D) heterostructure of ultrathin ZnIn2S4 nanosheets decorated with amorphous nickel boride (Ni x -B) is prepared for simultaneous photocatalytic anaerobic H2 generation and aromatic aldehydes production. This ZnIn2S4/Ni x -B catalyst elaborately combines the ultrathin structure advantage of the ZnIn2S4 semiconductor and the cocatalytic function of Ni x -B. A high H2 production rate of 8.9 mmol h–1 g–1 is delivered over the optimal ZnIn2S4/Ni x -B with a stoichiometric production of benzaldehyde, which is about 22 times higher than ZnIn2S4. Especially, the H2 evolution rate is much higher than the value (2.8 mmol h–1 g–1) of the traditional photocatalytic half reaction of H2 production with triethanolamine as a sacrificial agent. The apparent quantum yield reaches 24% at 420 nm, representing an advanced photocatalyst system. Moreover, compared with traditional sulfide, hydroxide, and even noble metal modified ZnIn2S4/M counterparts (M = NiS, Ni­(OH)2, Pt), the ZnIn2S4/Ni x -B also maintains markedly higher photocatalytic activity, showing a highly efficient and economical advantage of the Ni x -B cocatalyst. This work sheds light on the exploration of 2D ultrathin semiconductors decorated with novel transition metal boride cocatalyst for efficient photocatalytic organic transformation integrated with solar fuel production.

The difficulty of adsorption and activation of CO2 at the catalytic site and rapid recombination of photogenerated charge carriers severely restrict the CO2 conversion efficiency. Here, we fabricate a novel alkaline Co­(OH)2-decorated ultrathin 2D titanic acid nanosheet (H2Ti6O13) catalyst, which rationally couples the structural and functional merits of ultrathin 2D supports with catalytically active Co species. Alkaline Co­(OH)2 beneficially binds and activates CO2 molecules, while monolayer H2Ti6O13 acts as an electron relay that bridges a photosensitizer with Co­(OH)2 catalytic sites. As such, photoexcited charges can be efficiently channeled from light absorbers to activated CO2 molecules through the ultrathin hybrid Co­(OH)2/H2Ti6O13 composite, thereby producing syngas (CO/H2 mixture) from photoreduction of CO2. High evolution rates of 56.5 μmol h–1 for CO and 59.3 μmol h–1 for H2 are achieved over optimal Co­(OH)2/H2Ti6O13 by visible light illumination. In addition, the CO/H2 ratio can be facilely tuned from 1:1 to 1:2.4 by changing the Co­(OH)2 content, thus presenting a feasible approach to controllably synthesize different H2/CO mixtures for target applications.

Photocatalytic H2 evolution from haloid acid (HX) solution by metal halide perovskites (MHPs) has been intensively investigated; however, the corrosive acid solution severely restricts its practical operability. Therefore, developing acid-free schemes for H2 evolution using MHPs is highly desired. Here, we investigate the photocatalytic anaerobic dehydrogenation of alcohols over a series of MHPs (APbX3, A = Cs+, CH3NH3 + (MA), CH­(NH2)2 + (FA); X = Cl–, Br–, I–) to simultaneously produce H2 and aldehydes. Via the coassembly of Pt and rGO nanosheets on MAPbBr3 microcrystals, the optimal MAPbBr3/rGO-Pt reaches a H2 evolution rate of 3150 μmol g–1 h–1 under visible light irradiation (780 nm ≥ λ ≥ 400 nm), which is more than 105-fold higher than pure MAPbBr3 (30 μmol g–1 h–1). The present work not only brings new ample opportunities toward photocatalytic H2 evolution but also opens up new avenues for more effective utilization of MHPs in photocatalysis.

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