at the anode and cathode can actually 'self-neutralize' each other, leading to enhanced an electrochemical behaviour as described in Figure . We here demonstrated, visually in Figure , that the water splitting under neutral non-buffered conditions causes a rapid and sharp increase in the acidity/alkalinity at anode/cathode surfaces, however, the influence of distance between the electrodes is yet to be studied. For this purpose, two opto-electrochemical cells configurations were investigated, with different inter-electrode distances of ⁓700 µm (far) and ⁓400 µm (close), and the in-situ spatiotemporal visualization for the comparative resulting pH changes was performed under excitation wavelengths of 395nm and 440nm (Figure ).