Chinese scholars have made progress in imaging the charge separation and transport process of photocatalyst particles at the full spatiotemporal scale

Figure Full-time space-space dynamic "image" of the process of photogenerated charge separation of a single photocatalytic particle from femtoseconds to seconds

With the support of the National Natural Science Foundation of China (Grant No.
: 22088102), the team of Academician Li Can and Fan Fengtao, Academician Li Can and Fan Fengtao of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, have made progress in imaging the charge separation and transport process of photocatalyst particles photocatalyst particles" was published Oct.
12 in
the journal Nature.
Links to papers: _istranslated="1">.

Solar photocatalytic reaction can decompose water to produce hydrogen and reduce carbon dioxide to produce solar fuel, which is a "holy grail" topic in the field of science and has attracted worldwide attention
.
Although great efforts have been made in the preparation of photocatalysts and the study of photocatalytic reactions, the basic microscopic processes of photocatalysts have been unclear
due to the separation, transfer and spatiotemporal complexity of participating in chemical reactions in photocatalytic reactions.

In view of the above problems, the research team selectively synthesized the defective structure to a specific crystal plane of the particles, and used a variety of advanced characterization techniques and theoretical simulations such as time-resolved photoemission microscopy (femtoseconds to nanoseconds), transient surface photovoltage spectroscopy (nanoseconds to microseconds) and surface photovoltage microscopy (microseconds to seconds) to trace the whole process of separation and transfer evolution of photogenerated charges in nanoparticle photocatalysts in the whole space-time domain.
It is found that the anisotropic crystal planes and trapping states (such as defective structures) commonly present in photocatalysts directly affect the photogenerated charge kinetic behavior
.
The results show that the defective structure with spatial selectivity promotes effective charge separation, photogenerated electrons can be selectively transferred to the characteristic crystal plane region on subpicosecond time scales, and electrons can be transferred from one surface to another on ultrafast time scales, and the charge transfer of this ultrafast process is attributed to a new quasi-ballistic transport mechanism, showing quantum characteristics (Fig).

As the timescale progresses from nanoseconds to microseconds, holes appear on crystal planes
containing defective structures.

This kind of spatiotemporal tracking charge transfer research will greatly promote the understanding of the complex mechanism in the energy conversion process, and provide new ideas and strategies
for rationally designing photocatalysts with better performance.