Pcf8574t - What Is Pcf8574t?

The PCF8574 device provides general-purpose remote I/O expansion for most microcontroller families by way of the I2C interface [serial clock (SCL), serial data (SDA)].

What is the name of the IC to expand I o capability?

The BD3376MUV-M from ROHM is an I/O expansion IC that is intended for monitoring pushbuttons.