Bank 1 means passenger side, and sensor 2 means the downstream sensor, after the catalytic converter. Since you need the downstream right sensor, try searching with the following keywords: 01 qx4 oxygen sensor downstream right (or passenger). Then choose the brand you prefer.
Here is an example:
http://www.ebay.com/itm/WALKER-Downstre ... b7&vxp=mtr
However, you have to be careful to make sure that the part fits your particular vehicle. Use the compatibility chart to make sure your vehicle is listed.
As frapjap stated, a parts website such as Rockauto will ask what car you're shopping for before giving you any results, ensuring that you find a part which will fit your vehicle. So unless you know exactly what you need, it's better to look at this kind of site first.