ESP8266 GPIO pin improvement

Question

Is it possible to make this connection to an ESP8266 pin?

I saw this at Ruggeduino and tried to implement it for the ESP8266.

Below is the schematic:

Here's my reference:

This type of diode:

Here's my whole schematic:

Here's the PCB looks like:

TOP SIDE

BOT SIDE

Answer 1

That topology works for 5V and above, but 3.3V Zener diodes are pretty sloppy. They have very soft knee and they vary a lot on when they will start conducting.
A better approach at this and lower voltages would be to use two Schottky diodes connected to the power rails.

^{simulate this circuit – Schematic created using CircuitLab}