Co₃O₄ nanoforest/Ni foam as the interface heating sheet for the efficient solar-driven water evaporation under one sun

Solar-driven water evaporation is a near-perfect utilization of solar energy and a promising solution for water shortage. However, the sunlight-induced evaporation must rely on advanced photothermal conversion materials. In this article, we succeeded in synthesizing commercial Ni foam loading Co₃O₄ with nanoscale superstructures via hydrothermal-calcination method and studied photothermal conversion performance of this composite. The band gap of Co₃O₄ is relatively narrow and the multi-level nanostructures anchored on 3D Ni-skeleton increase light–matter interaction length and absorption times, so the Co₃O₄/Ni foam exhibits excellent light absorption. In the solar -driven water evaporation experiment, the highest evaporation rate is up to 1.226 kg m⁻² h⁻¹ and the highest photothermal conversion efficiency is over 80% under the illumination density of 1 kW m⁻². After many circular tests, there is not significant decline in efficiency. Based on this, the Ni foam loading Co₃O₄ nanoforest is a prospective candidate for solar photothermal conversion material.