Utilizing the broad‐band solar spectrum for sea water desalination is a promising method that can provide fresh water without sophisticated infrastructures. However, the solar‐to‐vapour efficiency has been limited due to the lack of a proper design for the evaporator to deal with either a large amount of heat loss or salt accumulation. Here, these issues are addressed via two cost‐effective approaches: I) a rational design of a concave shaped supporter by 3D‐printing that can promote the light harvesting capacity via multiple reflections on the surface; II) the use of a double layered photoabsorber composed of a hydrophilic bottom layer of a polydopamine (PDA) coated glass fiber (GF/C) and a hydrophobic upper layer of a carbonized poly(vinyl alcohol)/polyvinylpyrrolidone (PVA/PVP) hydrogel on the supporter, which provides competitive benefit for preventing deposition of salt while quickly pumping the water. The 3D‐printed solar evaporator can efficiently utilize solar energy (99%) with an evaporation rate of 1.60 kg m–2 h–1 and efficiency of 89% under 1 sun irradiation. The underlying reason for the high efficiency obtained is supported by the heat transfer mechanism. The 3D‐printed solar evaporator could provide cheap drinking water in remote areas, while maintaining stable performance for a long term.

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The use of oxygen evolution co-catalysts (OECs) with hematite photoanodes has received much attention because of the potential to reduce surface charge recombination. However, the low surface charge transfer and bulk charge separation rate of hematite are not improved by decorating with OECs, and the intrinsic drawbacks of hematite still limit efficient photoelectrochemical (PEC) water splitting. Here, we successfully overcame the sluggish oxygen evolution reaction performance of hematite for water splitting by inserting zero-dimensional (0D) nanofragmented MXene (NFMX) as a hole transport material between the hematite and the OEC. The 0D NFMX was fabricated from two-dimensional (2D) MXene sheets and deposited onto the surface of a three-dimensional (3D) hematite photoanode via a centrifuge-assisted method without altering the inherent performance of the 2D MXene sheets. Among many OECs, NiFe­(OH) x was selected as the OEC to improve hematite PEC performance in our system because of its efficient charge transport behavior and high stability. Because of the great synergy between NFMX and NiFe­(OH) x , NiFe­(OH) x /NFMX/Fe2O3 achieved a maximum photocurrent density of 3.09 mA cm–2 at 1.23 VRHE, which is 2.78-fold higher than that of α-Fe2O3 (1.11 mA cm–2). Furthermore, the poor stability of MXene in an aqueous solution for water splitting was resolved by uniformly coating it with NiFe­(OH) x , after which it showed outstanding stability for 60 h at 1.23 VRHE. This study demonstrates the successful use of NFMX as a hole transport material combined with an OEC for highly efficient water splitting.

Solar Evaporators In article number 2102649, Ji‐Hyun Jang and co‐workers present a 3D‐printed solar evaporator that can efficiently utilize solar energy (99%) with an evaporation rate of 1.60 kg m−2 h−1 and efficiency of 89% under 1 sun irradiation, which promotes light‐harvesting capacity via multiple reflections on the surface and provides competitive benefits for preventing deposition of salt while quickly pumping the water, for long‐term provision of drinking water in remote locations.

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