Macroporous transport – mesoporous catalysis: a rapid microfluidic-fabricated biomimetic sponge photocatalytic microsphere reactor

To address the low light-harvesting efficiency, rapid charge recombination, and restricted mass transport in conventional photocatalysts, this study proposes a bio-inspired SiO2@TiO2 photocatalytic microsphere reactor (ST-PCMR), rapidly fabricated via microfluidic technology and confined self-assembly. This reactor employs an ordered macroporous SiO2 framework as a mechanical support and a rapid mass transfer channel, while a high-surface-area interconnected mesoporous TiO2 catalytic network is constructed under spatial confinement. By tuning the size of the SiO2 nanoparticles, the photonic band-gap was precisely matched with the absorption edge of TiO2, significantly enhancing light absorption via the slow-photon effect. The confinement effect further induced the formation of Ti–O–Si bonded interfaces and high-density grain boundaries, which effectively accelerated the separation and suppressed the recombination of photogenerated charge carriers, leading to a significant increase in photocurrent density and a notable reduction in charge-transfer resistance compared to non-confined TiO2. Under identical illumination conditions, the ST-PCMR exhibited excellent hydrogen production performance, showing an activity 8 times higher than that of single-component TiO2, with 86% retention of its initial activity after five cycles. This study provides a new material paradigm for synergistically optimizing light harvesting, charge separation, and reaction transport, offering a promising pathway for highly efficient solar-to-hydrogen conversion.