Using samples of Co100-xTbx/Cu/Y3Fe5O12, we investigate the heat-to-charge current conversion phenomena in amorphous Co100-xTbx alloys. We find an enhancement of the inverse spin Hall voltage owing to the Tb impurity by means of the spin Seebeck effect. The spin Hall angle of Co68Tb32 is 3.5 times larger than that of Co, and mainly originates from the extrinsic spin Hall effect. Meanwhile, we detect an anomalous Nernst voltage owing to the magnetic properties of Co100-xTbx alloy. The sign of the inverse spin Hall voltage is observed to be the same for all Co100-xTbx samples, whereas the anomalous Nernst voltage changes its sign around the magnetization compensation composition. Our finding proves Co100-xTbx is an efficient spin-to-charge current convertor, and it has advantages for manipulating not only the inverse spin Hall effect but also the anomalous Nernst effect by means of adjusting the Tb concentration.