Zhi Jiang

Facet engineering is an effective strategy for enhancing the photocatalytic performance of semiconductor single crystals. However, conventional high-temperature solid-state synthesis often suffers from coupled crystallization and grain coarsening, making it difficult to simultaneously achieve high crystallinity, controlled facet exposure, small particle size, and good dispersibility. Herein, we report an integrated strategy combining solid-state recrystallization and facet engineering for the synthesis of small-sized SrTiO3:Rh single crystals with co-exposed (100)/(110) facets. Specifically, this approach employs partially crystallized SrTiO3 nanosphere precursors, which are subsequently subjected to SrCl2 molten-salt-assisted high-temperature recrystallization to enable crystal reconstruction, while suppressing excessive grain growth. The incorporation of Rh, together with the SrCl2 molten-salt environment, influences crystal growth behavior and facilitates selective facet exposure, which is associated with the formation of octadecahedral SrTiO3:Rh single crystals. The resulting particles simultaneously exhibit high crystallinity, anisotropic facet exposure, reduced particle size, and enhanced suspension stability in aqueous media. These structural features are closely correlated with improved charge carrier separation behavior and higher mass-normalized activity under low catalyst loading conditions. Compared with conventional Rh2O3-derived SrTiO3:Rh, the optimized samples exhibit significantly enhanced charge separation behavior and photocatalytic hydrogen evolution performance. Furthermore, upon Cr co-doping, the SrTiO3:Rh,Cr/BiVO4 system with the highest activity among the investigated Cr concentrations, coupled with the Fe3+/Fe2+ redox mediator, achieves an apparent quantum yield (AQY) of 4% under 420 nm monochromatic irradiation and demonstrates stable overall water splitting activity in a liquid-phase Z-scheme configuration.

The oxygen evolution reaction represents the primary kinetic bottleneck in photoelectrochemical water splitting and typically necessitates an external bias. The fundamental impact of charge accumulation induced by applied overpotential remains insufficiently understood. This work identified that the excess accumulation of surface-positive charges on BiVO₄ photoanodes acts as a detrimental kinetic barrier that impedes water oxidation. The construction of a NiO-BiVO₄ p-n junction could facilitate electron migration toward the photoanode surface to effectively neutralize excess positive charge and modulate the polarizability of V-O bonds. In situ Raman spectra reveal the formation of high-valent Ni⁴⁺ species within NiOOH⁺ stabilized the V-O bond polarizability. Consequently, the photoanode achieved a photocurrent density of 6.48 mA cm^-2 at 1.23 V_RHE. This work revealed that rational regulation of interfacial charge density via p-n junction engineering was critical for stabilizing key bond polarizabilities, providing a general strategy to overcome kinetic limitations in solar energy conversion.

Rapid, nonequilibrium heating drives mesoscale structural evolution in heterogeneous composite materials under extreme thermal conditions, critically influencing performance in aerospace propulsion and advanced structural applications. However, existing experimental techniques lack the capability to directly observe heterogeneous structural evolution and intercomponent interactions under controlled conditions that closely mimic realistic nonequilibrium thermal fronts. Consequently, theoretical models, which assume equilibrium conditions or neglect dynamic structural evolution, remain insufficiently validated and cannot accurately predict these critical transformation pathways. Here, we developed a gradiated fast-heating system (>20 °C/s) enabling precise control of heating rate gradients within submillimeter transition regions in a single specimen, seamlessly integrated with sequential synchrotron X-ray tomography and radiography to directly visualize internal structural evolution. This approach allowed capture of diverse structural transformation pathways spanning microsecond-to-millisecond timescales under distinct nonequilibrium thermal conditions, revealing the complete sequence from initial pyrolysis through ignition to final burnout. We found that local heating rates, rather than bulk temperatures, dictate void formation dynamics and fragmentation pathways. In regions with high local heating rates, rapid void nucleation within the binder phase created reticulated porous networks, evolving four times faster than curved interfacial voids observed in adjacent regions experiencing lower heating rates. Furthermore, a cascade of heterogeneous component interactions subsequently fragmented the metallic network into isolated clusters, seeding critical ignition hotspots that governed combustion initiation and propagation mechanisms. These findings indicate that kinetic processes, influenced notably by heating rate, play an important role in mesostructural evolution under nonequilibrium conditions.

N-type sulfide semiconductors are promising photocatalysts due to their broad visible-light absorption, facile synthesis and chemical diversity. However, photocorrosion and limited electron transport in one-step excitation and solid-state Z-scheme systems hinder efficient overall water splitting. Liquid-phase Z-schemes offer a viable alternative, but sluggish mediator kinetics and interfacial side reactions impede their construction. Here we report a stable Z-scheme system integrating n-type CdS and BiVO₄ with a [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ mediator, achieving 10.2% apparent quantum yield at 450 nm with stoichiometric H₂/O₂ evolution. High activity reflects synergies between Pt@CrO_x and Co₃O₄ cocatalysts on CdS, and cobalt-directed facet asymmetry in BiVO₄, resulting in matched kinetics for hydrogen and oxygen evolution in a reversible mediator solution. Stability is dramatically improved through coating CdS and BiVO₄ with different oxides to inhibit Fe₄[Fe(CN)₆]₃ precipitation and deactivation by a hitherto unrecognized mechanism. Separate hydrogen and oxygen production is also demonstrated in a two-compartment reactor under visible light and ambient conditions. This work unlocks the long-sought potential of n-type sulfides for efficient, durable and safe solar-driven hydrogen production.

• The detailed mechanism of toluene destruction in an NTP system was revealed by SVUV-PIMS and quantum chemistry. • The decomposition processes of toluene and benzene in the NTP process were compared in detail. • The methyl group in the toluene changed the stability of the molecular structure. • The methyl group in the toluene participates in or initiates reaction pathways different from benzene only system. • O-benzoquinone was identified as an important intermediate contributing to the difference of reactions between toluene and benzene decomposition processes.