NFC in Android is not active while the device is locked [0]

> Android-powered devices are usually looking for NFC tags when the screen is unlocked, unless NFC is disabled in the device's Settings menu.

So to use this, the hacker already needs an unlocked device, in which case it's just as easy to download the payload directly.

Usually, the range for NFC to work is quite close, 4 cm or less [1], and I don't think these chips have the capability to increase the range.

[0]: http://developer.android.com/guide/topics/connectivity/nfc/n...

[1]: https://developer.android.com/guide/topics/connectivity/nfc/...