Facile synthesis and thermoelectric performance of BiCu1-xSeO

•Thermoelectric oxide BiCuSeO was facile prepared by one-step high-pressure method.•The sample contains fine grains and a large number of multiscale nanoparticles.•An extremely low thermal conductivity and enhanced ZT of BiCuSeO was obtained. BiCuSeO based materials have been drawn much attention since they were found to be excellent thermoelectric materials recently. Apart from high performance, the time and energy-efficient synthesis of BiCuSeO is also essential for its commercialization. In this paper, a simple one-step high pressure method was used to quickly synthesize the copper-deficient BiCuSeO. The introduction of Cu vacancy improves the carrier concentration and power factor. Through the phonon scattering of fine grains and crystal defects caused by Cu deficiency and high pressure compression, an extremely low phonon thermal conductivity of BiCu0.94SeO ~ 0.3 Wm−1K−1 @ 750 K is obtained. An enhanced ZT ~ 0.87 at 750 K is obtained for BiCu0.94SeO. This value is twice higher than that of the original BiCuSeO, compared with the traditional time-consuming method.