Extensive energy conversion of solar energy can only be achieved by
large-scale collection of solar flux. The technology that satisfies this
requirement must be as simple as possible to reduce capital cost.
Overall water splitting by powder-form photocatalysts directly produces a
mixture of H2 and O2 (chemical energy) in a
single reactor, which does not require any complicated parabolic mirrors
and electronic devices. Because of its simplicity and low capital cost,
it has tremendous potential to become the major technology of solar
energy conversion. Development of highly efficient photocatalysts is
desired. This review addresses why visible light responsive
photocatalysts are essential to be developed. The state of the art for
the photocatalysts for overall water splitting is briefly described.
Moreover, various fundamental aspects for developing efficient
photocatalysts, such as particle size of photocatalysts, cocatalysts,
and reaction kinetics are discussed.