Do when I attack triggers occur when moving into an empty battlefield?

No, "When I attack" triggers do not occur when moving into an empty battlefield.

According to the rules and FAQs:

• Combat is required: "When I attack" triggers only activate when a unit gains the Attacker designation. This designation is only granted during Combat.
• Empty battlefields are not Combat: Moving a unit to an empty (unoccupied) battlefield initiates a non-combat Showdown, not a Combat. Because there is no opposing unit to create a Combat, your unit does not gain the "Attacker" designation.
• Trigger conditions: As stated in FAQ #2505 and FAQ #6821, "When I attack" triggers do not activate when moving to an empty or uncontrolled battlefield. They specifically require the unit to be designated as an attacker, which occurs when moving to a battlefield occupied by an opponent's unit.