Carbon nanotubes (CNTs) are well known as excellent electrical conductors. However, their transport properties are limited by electrical breakdown in ambient. Moreover, the electronic properties can further be modulated by doping. Devices such as Schottky diodes, transistors and logic gates based on un-doped and doped CNT junctions have been realized. Recently, nitrogen doped CNTs show potential application in replacing platinum cathode catalyst in fuel cell technology. We synthesize pristine, nitrogen-doped and nitrogen-doped:pristine CNT intratubular junctions by one-step co-pyrolysis and explore them for different applications. We show that the position of electrical breakdown can be predicted which is essential to know for high current applications. Among other applications, we show that individual CNT intratubular junction exhibits rectifying characteristics. Further investigation indicates the intratubular junction behaves like Schottky diode. Lastly, the potential replacement of platinum by nitrogen doped CNTs in direct methanol fuel cell has been explored.