2D monoelemental
materials, particularly germanene and
silicene
(the single layer of germanium and silicon), which are the base materials
for modern electronic devices demonstrated tremendous attraction for
their 2D layer structure along with the tuneable electronics and optical
band gap. The major shortcoming of synthesized thermodynamically very
unstable layered germanene and silicene with their inclination toward
oxidation was overcome by topochemical deintercalation of a Zintl
phase (CaGe2, CaGe1.5Si0.5, and CaGeSi)
in a protic environment. The
exfoliated Ge–H, Ge0.75Si0.25H, and Ge0.5Si0.5H were successfully synthesized and employed
as the active layer for photoelectrochemical photodetectors, which
showed broad response (420–940 nm), unprecedented responsivity,
and detectivity on the order of 168 μA W–1and 3.45 × 108cm Hz1/2W–1, respectively. The sensing capability of exfoliated germanane and
silicane composites was explored using electrochemical impedance spectroscopy
with ultrafast response and recovery time of less than 1 s. These
positive findings serve as the application of exfoliated germanene
and silicene composites and can pave a new path to practical applications
in efficient future devices.