(1) According to the characteristics of major element types in the law of conservation of mass, it can be known that hydrogen reacts with germanium trioxide under heating conditions to generate germanium and water. The chemical equation of this reaction is: 2H 2 +GeO 2 △. Ge+2H 2 O

According to the meaning of the question, the reaction is to generate hydrogen and oxygen by decomposing water, which means that nickel-containing oxides do not participate in the reaction, but only play a catalytic role. Water reacts with nickel-containing oxides under catalysis and illumination to generate hydrogen and oxygen. The chemical equation of this reaction is: 2H·2o? Nickel oxide? Visible light 2H 2 ↑+O 2 ↑. ..

So the answer is: (1)2H 2+ geography 2 △. ge+2H 2o； (2) catalysis; 2H 2 O？ Nickel oxide? Visible light 2H 2 ↑+O 2 ↑. ..