Do you mean all 8 surrounding elements?
x = randi([0,5], 22, 22); % Example data
Z = conv2(double(x == 0), ones(3, 3), 'same');
x(Z ~= 0) = 0;
If you mean the 4 neighbors without the diagonals:
Z = conv2(double(x == 0), [0,1,0; 1,0,1; 0,1,0], 'same');
x(Z ~= 0) = 0;
