  The estimation of the binary fraction of hot subdwarfs is key to shed light
on the different evolution scenarios proposed to explain the loss of the
hydrogen envelope during the red giant branch phase. In this paper we analyse
the spectral energy distribution of the hot subdwarfs included in a recent and
comprehensive catalogue with the aim of identifying companions. Our methodology
shows a performance superior to the photometric criteria used in that study,
identifying 202 objects wrongly classified as binaries according to their
spectral energy distributions, and finding 269 new binaries. Out of an initial
sample of 3186 objects, we classified 2469 as single and 615 as binary hot
subdwarfs. The rest of the objects (102) were not classified because of their
inadequate spectral energy distribution fitting due, in turn, to poor quality
photometry. Effective temperatures, luminosities and radii were computed for
192 singles and 42 binaries. They, in particular the binary sample, constitute
an excellent dataset to further perform a more careful spectroscopic analysis
that could provide detailed values for the chemical composition, masses, ages,
rotation properties or reflection effects for the shortest-period systems. The
results obtained in this paper will be used as a reference for a forthcoming
work where we aim to generalize binary and single hot subdwarf classification
using Artificial Intelligence-based techniques.
