Less than 24h in Shanghai for transit

My wife and I are going to Cambodia and Vietnam in two weeks. We are going through Shanghai, where we will be a little under 24 hours on the way to Cambodia and less than 6 hours on the way back to the US. My wife is a US citizen, while I hold a UK passport. We plan to spend the night in a Shanghai Hotel (during the 23h visit), and stay in the airport for the 2nd transit. Is my interpretation correct that my wife (US) does NOT need a Visa, while I (UK) will need a transit visa?